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如何找到&使用 Valgrind 检查后，删除 C 程序中的内存泄漏和错误

发布于 2024-12-16 21:02:09 字数 10743 浏览 0 评论 0原文

用 Valgrind 检查我的代码后，它显示了很多错误消息和信息，我不确定如何查找和删除代码中的错误？

我的源代码如下。

myheader.h

 #include<stdlib.h>
 #define MAX 15
 typedef enum
 {
  METROPOLITAN_AREA,
  TOURIST_AREA,
 }area_type_t;

 typedef struct
 {
  int population;
  int area;
 }metropolitan_t;

 typedef struct
 {
  char *type_place;
  char *near_airport;
 }tourist_t;

 typedef struct
 {
  char *name;
  char *country;
  area_type_t area_t;
  union
  {
      metropolitan_t metro;
      tourist_t   tourist;
  }u;

 }*place_t;
 extern void get_input(place_t);

getinput.c

#include<myheader.h>
void get_input(place_t place)
{
 int check=1;
 int num,i,ch;
 printf("\nEnter the no of records : \n");
 scanf("%d",&num);
 place=(place_t)malloc(sizeof(place_t)*num);
 if(NULL==place)
 {
  printf("\nMemory allocation failed\n");
  exit(1);
 }
 for(i=0;i<num;i++)
 {
  printf("\nEnter the place name : ");
  place->name=(char *)malloc(sizeof(char)*MAX);
  if(NULL==place->name)
  {
   free(place);
   printf("\nMemory allocation failed\n");
   exit(1);
  }
  scanf("%s",place->name);
  printf("\nEnter the coutry name : ");
  place->country=(char *)malloc(sizeof(char)*MAX);
  if(NULL==place->country)
  {
   free(place);
   free(place->name);
   printf("Memory allocation failed\n");
   exit(1);
  }
  scanf("%s",place->country);
   printf("\nPlease Enter '0' if the place is Metropolitan, '1' if the place Tourist place\n");
   scanf("%d",&ch);
  while(check)
  {
   switch(ch)
   {
    case 0:
     check=0;
     place->area_t=METROPOLITAN_AREA;
     break;
    case 1:
     check=0;
     place->area_t=TOURIST_AREA;
      break;
    default:
     printf("\nPlease enter valid choice \n");
   }
  }
  if(place->area_t==METROPOLITAN_AREA)
  {
    printf("\nEnter the population of the place : ");
    scanf("%d",&(place->u.metro.population));
    printf("\nEnter the area of place :"); 
    scanf("%d",&(place->u.metro.area));
  } else
  {
   printf("\nEnter the nearest airport name : ");
   place->u.tourist.near_airport=(char *)malloc(sizeof(char)*MAX);
   if(NULL==place->u.tourist.near_airport)
   {
    printf("Memory allocation failed\n");
    exit(1);
   }
   scanf("%s",(place->u.tourist.near_airport));
   printf("\nEnter the type of tourist spot : ");
   place->u.tourist.type_place=(char *)malloc(sizeof(char)*MAX);

   if(NULL==place->u.tourist.type_place)
   {
    printf("Memory allocation failed\n");
    exit(1);
   }
   scanf("%s",(place->u.tourist.type_place));
  }
  check=1;
  place++;
 }
}

ma​​in.c

#include"myheader.h"
int main()
{
 place_t place;
 get_input(place);
 return 0;
}

命令行记录

 bash-3.00$ valgrind --tool=memcheck --leak-check=yes --show-reachable=yes a.out
 ==13514== Memcheck, a memory error detector.
 ==13514== Copyright (C) 2002-2005, and GNU GPL'd, by Julian Seward et al.
 ==13514== Using LibVEX rev 1575, a library for dynamic binary translation.
 ==13514== Copyright (C) 2004-2005, and GNU GPL'd, by OpenWorks LLP.
 ==13514== Using valgrind-3.1.1, a dynamic binary instrumentation framework.
 ==13514== Copyright (C) 2000-2005, and GNU GPL'd, by Julian Seward et al.
 ==13514== For more details, rerun with: -v
 ==13514==

 Enter the no of records :
 2

 Enter the place name : Banglore

 Enter the coutry name : India

 Please Enter '0' if the place is Metropolitan, '1' if the place Tourist place
 0
 ==13514== Invalid write of size 4
 ==13514==    at 0x400789: get_input (getinput.c:43)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D040 is 0 bytes after a block of size 16 alloc'd
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x400637: get_input (getinput.c:8)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514== Invalid read of size 4
 ==13514==    at 0x4007BB: get_input (getinput.c:53)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D040 is 0 bytes after a block of size 16 alloc'd
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x400637: get_input (getinput.c:8)
 ==13514==    by 0x4005E8: main (main.c:5)

 Enter the population of the place : 303030

 Enter the area of place :2500
 ==13514==
 ==13514== Invalid write of size 8
 ==13514==    at 0x40068C: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D058 is not stack'd, malloc'd or (recently) free'd
 ==13514==
 ==13514== Invalid read of size 8
 ==13514==    at 0x400693: get_input (getinput.c:18)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D058 is not stack'd, malloc'd or (recently) free'd
 ==13514==
 ==13514== Invalid read of size 8
 ==13514==    at 0x4006BF: get_input (getinput.c:24)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D058 is not stack'd, malloc'd or (recently) free'd

 Enter the place name : London

==13514==
 ==13514== Invalid write of size 8
 ==13514==    at 0x4006EE: get_input (getinput.c:26)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D060 is 16 bytes before a block of size 15 alloc'd
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40068B: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514== Invalid read of size 8
 ==13514==    at 0x4006F6: get_input (getinput.c:27)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514== Invalid read of size 8
 ==13514==    at 0x4006F6: get_input (getinput.c:27)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D060 is 16 bytes before a block of size 15 alloc'd
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40068B: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514== Invalid read of size 8
 ==13514==    at 0x40072F: get_input (getinput.c:34)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D060 is 16 bytes before a block of size 15 alloc'd
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40068B: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)

 Enter the coutry name : London

 Please Enter '0' if the place is Metropolitan, '1' if the place Tourist place
 1
 ==13514==
 ==13514== Invalid write of size 4
 ==13514==    at 0x40079D: get_input (getinput.c:47)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D068 is 8 bytes before a block of size 15 alloc'd
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40068B: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)

 ==13514==
 ==13514== Invalid write of size 8
 ==13514==    at 0x40082F: get_input (getinput.c:62)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D078 is 8 bytes inside a block of size 15 alloc'd
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40068B: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514== Invalid read of size 8
 ==13514==    at 0x400837: get_input (getinput.c:63)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D078 is 8 bytes inside a block of size 15 alloc'd
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40068B: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514== Invalid read of size 8
 ==13514==    at 0x40085B: get_input (getinput.c:68)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D078 is 8 bytes inside a block of size 15 alloc'd
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40068B: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)

 Enter the nearest airport name : London

 Enter the type of tourist spot : Entertainment

 ==13514==
 ==13514== ERROR SUMMARY: 13 errors from 12 contexts (suppressed: 4 from 1)
 ==13514== malloc/free: in use at exit: 106 bytes in 7 blocks.
 ==13514== malloc/free: 7 allocs, 0 frees, 106 bytes allocated.
 ==13514== For counts of detected errors, rerun with: -v
 ==13514== searching for pointers to 7 not-freed blocks.
 ==13514== checked 75,768 bytes.
 ==13514==
 ==13514==
 ==13514== 15 bytes in 1 blocks are indirectly lost in loss record 1 of 7
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40088A: get_input (getinput.c:70)
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40088A: get_input (getinput.c:70)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514==
 ==13514== 15 bytes in 1 blocks are definitely lost in loss record 2 of 7
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40082E: get_input (getinput.c:62)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514==
 ==13514== 15 bytes in 1 blocks are definitely lost in loss record 3 of 7
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x4006ED: get_input (getinput.c:26)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514==
 ==13514== 15 bytes in 1 blocks are definitely lost in loss record 4 of 7
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40068B: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514==
 ==13514== 15 bytes in 1 blocks are indirectly lost in loss record 5 of 7
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x4006ED: get_input (getinput.c:26)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514==
 ==13514== 15 bytes in 1 blocks are indirectly lost in loss record 6 of 7
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40068B: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514==
 ==13514==
 ==13514== 61 (16 direct, 45 indirect) bytes in 1 blocks are definitely lost in loss record 7 of 7
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x400637: get_input (getinput.c:8)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514== LEAK SUMMARY:
 ==13514==    definitely lost: 61 bytes in 4 blocks.
 ==13514==    indirectly lost: 45 bytes in 3 blocks.
 ==13514==      possibly lost: 0 bytes in 0 blocks.
 ==13514==    still reachable: 0 bytes in 0 blocks.
 ==13514==         suppressed: 0 bytes in 0 blocks.

我该如何解决这个问题并制作我的程序内存效率更高？我使用的 malloc() 语句有什么问题吗？

原文

After checked my code with Valgrind, it shows a lot of error messages and information and I am not sure about how to find and remove the errors in code?

My source code is as follows.

myheader.h

 #include<stdlib.h>
 #define MAX 15
 typedef enum
 {
  METROPOLITAN_AREA,
  TOURIST_AREA,
 }area_type_t;

 typedef struct
 {
  int population;
  int area;
 }metropolitan_t;

 typedef struct
 {
  char *type_place;
  char *near_airport;
 }tourist_t;

 typedef struct
 {
  char *name;
  char *country;
  area_type_t area_t;
  union
  {
      metropolitan_t metro;
      tourist_t   tourist;
  }u;

 }*place_t;
 extern void get_input(place_t);

getinput.c

#include<myheader.h>
void get_input(place_t place)
{
 int check=1;
 int num,i,ch;
 printf("\nEnter the no of records : \n");
 scanf("%d",&num);
 place=(place_t)malloc(sizeof(place_t)*num);
 if(NULL==place)
 {
  printf("\nMemory allocation failed\n");
  exit(1);
 }
 for(i=0;i<num;i++)
 {
  printf("\nEnter the place name : ");
  place->name=(char *)malloc(sizeof(char)*MAX);
  if(NULL==place->name)
  {
   free(place);
   printf("\nMemory allocation failed\n");
   exit(1);
  }
  scanf("%s",place->name);
  printf("\nEnter the coutry name : ");
  place->country=(char *)malloc(sizeof(char)*MAX);
  if(NULL==place->country)
  {
   free(place);
   free(place->name);
   printf("Memory allocation failed\n");
   exit(1);
  }
  scanf("%s",place->country);
   printf("\nPlease Enter '0' if the place is Metropolitan, '1' if the place Tourist place\n");
   scanf("%d",&ch);
  while(check)
  {
   switch(ch)
   {
    case 0:
     check=0;
     place->area_t=METROPOLITAN_AREA;
     break;
    case 1:
     check=0;
     place->area_t=TOURIST_AREA;
      break;
    default:
     printf("\nPlease enter valid choice \n");
   }
  }
  if(place->area_t==METROPOLITAN_AREA)
  {
    printf("\nEnter the population of the place : ");
    scanf("%d",&(place->u.metro.population));
    printf("\nEnter the area of place :"); 
    scanf("%d",&(place->u.metro.area));
  } else
  {
   printf("\nEnter the nearest airport name : ");
   place->u.tourist.near_airport=(char *)malloc(sizeof(char)*MAX);
   if(NULL==place->u.tourist.near_airport)
   {
    printf("Memory allocation failed\n");
    exit(1);
   }
   scanf("%s",(place->u.tourist.near_airport));
   printf("\nEnter the type of tourist spot : ");
   place->u.tourist.type_place=(char *)malloc(sizeof(char)*MAX);

   if(NULL==place->u.tourist.type_place)
   {
    printf("Memory allocation failed\n");
    exit(1);
   }
   scanf("%s",(place->u.tourist.type_place));
  }
  check=1;
  place++;
 }
}

main.c

#include"myheader.h"
int main()
{
 place_t place;
 get_input(place);
 return 0;
}

Command-line transcript

 bash-3.00$ valgrind --tool=memcheck --leak-check=yes --show-reachable=yes a.out
 ==13514== Memcheck, a memory error detector.
 ==13514== Copyright (C) 2002-2005, and GNU GPL'd, by Julian Seward et al.
 ==13514== Using LibVEX rev 1575, a library for dynamic binary translation.
 ==13514== Copyright (C) 2004-2005, and GNU GPL'd, by OpenWorks LLP.
 ==13514== Using valgrind-3.1.1, a dynamic binary instrumentation framework.
 ==13514== Copyright (C) 2000-2005, and GNU GPL'd, by Julian Seward et al.
 ==13514== For more details, rerun with: -v
 ==13514==

 Enter the no of records :
 2

 Enter the place name : Banglore

 Enter the coutry name : India

 Please Enter '0' if the place is Metropolitan, '1' if the place Tourist place
 0
 ==13514== Invalid write of size 4
 ==13514==    at 0x400789: get_input (getinput.c:43)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D040 is 0 bytes after a block of size 16 alloc'd
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x400637: get_input (getinput.c:8)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514== Invalid read of size 4
 ==13514==    at 0x4007BB: get_input (getinput.c:53)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D040 is 0 bytes after a block of size 16 alloc'd
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x400637: get_input (getinput.c:8)
 ==13514==    by 0x4005E8: main (main.c:5)

 Enter the population of the place : 303030

 Enter the area of place :2500
 ==13514==
 ==13514== Invalid write of size 8
 ==13514==    at 0x40068C: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D058 is not stack'd, malloc'd or (recently) free'd
 ==13514==
 ==13514== Invalid read of size 8
 ==13514==    at 0x400693: get_input (getinput.c:18)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D058 is not stack'd, malloc'd or (recently) free'd
 ==13514==
 ==13514== Invalid read of size 8
 ==13514==    at 0x4006BF: get_input (getinput.c:24)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D058 is not stack'd, malloc'd or (recently) free'd

 Enter the place name : London

==13514==
 ==13514== Invalid write of size 8
 ==13514==    at 0x4006EE: get_input (getinput.c:26)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D060 is 16 bytes before a block of size 15 alloc'd
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40068B: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514== Invalid read of size 8
 ==13514==    at 0x4006F6: get_input (getinput.c:27)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514== Invalid read of size 8
 ==13514==    at 0x4006F6: get_input (getinput.c:27)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D060 is 16 bytes before a block of size 15 alloc'd
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40068B: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514== Invalid read of size 8
 ==13514==    at 0x40072F: get_input (getinput.c:34)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D060 is 16 bytes before a block of size 15 alloc'd
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40068B: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)

 Enter the coutry name : London

 Please Enter '0' if the place is Metropolitan, '1' if the place Tourist place
 1
 ==13514==
 ==13514== Invalid write of size 4
 ==13514==    at 0x40079D: get_input (getinput.c:47)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D068 is 8 bytes before a block of size 15 alloc'd
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40068B: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)

 ==13514==
 ==13514== Invalid write of size 8
 ==13514==    at 0x40082F: get_input (getinput.c:62)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D078 is 8 bytes inside a block of size 15 alloc'd
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40068B: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514== Invalid read of size 8
 ==13514==    at 0x400837: get_input (getinput.c:63)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D078 is 8 bytes inside a block of size 15 alloc'd
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40068B: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514== Invalid read of size 8
 ==13514==    at 0x40085B: get_input (getinput.c:68)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==  Address 0x4A2D078 is 8 bytes inside a block of size 15 alloc'd
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40068B: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)

 Enter the nearest airport name : London

 Enter the type of tourist spot : Entertainment

 ==13514==
 ==13514== ERROR SUMMARY: 13 errors from 12 contexts (suppressed: 4 from 1)
 ==13514== malloc/free: in use at exit: 106 bytes in 7 blocks.
 ==13514== malloc/free: 7 allocs, 0 frees, 106 bytes allocated.
 ==13514== For counts of detected errors, rerun with: -v
 ==13514== searching for pointers to 7 not-freed blocks.
 ==13514== checked 75,768 bytes.
 ==13514==
 ==13514==
 ==13514== 15 bytes in 1 blocks are indirectly lost in loss record 1 of 7
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40088A: get_input (getinput.c:70)
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40088A: get_input (getinput.c:70)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514==
 ==13514== 15 bytes in 1 blocks are definitely lost in loss record 2 of 7
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40082E: get_input (getinput.c:62)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514==
 ==13514== 15 bytes in 1 blocks are definitely lost in loss record 3 of 7
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x4006ED: get_input (getinput.c:26)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514==
 ==13514== 15 bytes in 1 blocks are definitely lost in loss record 4 of 7
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40068B: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514==
 ==13514== 15 bytes in 1 blocks are indirectly lost in loss record 5 of 7
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x4006ED: get_input (getinput.c:26)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514==
 ==13514== 15 bytes in 1 blocks are indirectly lost in loss record 6 of 7
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x40068B: get_input (getinput.c:17)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514==
 ==13514==
 ==13514== 61 (16 direct, 45 indirect) bytes in 1 blocks are definitely lost in loss record 7 of 7
 ==13514==    at 0x4904A06: malloc (vg_replace_malloc.c:149)
 ==13514==    by 0x400637: get_input (getinput.c:8)
 ==13514==    by 0x4005E8: main (main.c:5)
 ==13514==
 ==13514== LEAK SUMMARY:
 ==13514==    definitely lost: 61 bytes in 4 blocks.
 ==13514==    indirectly lost: 45 bytes in 3 blocks.
 ==13514==      possibly lost: 0 bytes in 0 blocks.
 ==13514==    still reachable: 0 bytes in 0 blocks.
 ==13514==         suppressed: 0 bytes in 0 blocks.

How can I resolve this and make my program more memory-efficient? Is there anything wrong in the malloc() statements that I used?

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这样的小城市 2024-12-23 21:02:09

首先要做的就是消除所有内存错误（缓冲区溢出）。第一个错误发生在 get_input.c 的第 45 行，因此请转到该行并找出问题所在。

肯定会出错的一件事是，

 place=(place_t)malloc(sizeof(place_t)*num);

您正在分配一个 place_t ，但是您已将 place_t 定义为：

typedef struct
{

 }*place_t;

即 place_t 只是一个指针。这意味着例如 malloc(sizeof(place_t)) 只是为指针分配空间，而不是为整个 place_t 分配空间。不要使用 typedef 将结构名称隐藏为指针，但如果必须，请将 malloc 语句更改为

     place=(place_t)malloc(sizeof *place)*num);

另一个问题是您 free() 结构，然后尝试访问其中的成员，这是无效的。

free(place);
free(place->name);

你必须按照这个顺序来做

free(place->name);
free(place);

你也会泄漏内存，例如这里：
for(i=0;iname=(char *)malloc(sizeof(char)*MAX);

2. 这个循环中的时间发生了什么？您分配给 place->name ，丢失了指向您在循环的第一次迭代中分配的内存的指针，也许您打算在循环内使用 place[num]，因为您尝试在 place=(place_t)malloc(sizeof(place_t)*num) 中分配许多 place_t。 ; 陈述。

The first thing to do is get rid of all the memory error(buffer overruns). The first error occurs in get_input.c at line 45, so go to that line and figure out what's going wrong.

One thing that's surely going wrong is this

 place=(place_t)malloc(sizeof(place_t)*num);

You're allocating a place_t , however you have defined a place_t as this:

typedef struct
{

 }*place_t;

i.e. a place_t is just a pointer. That means that e.g. malloc(sizeof(place_t)) just allocates space for a pointer, not for a whole place_t. Don't hide structs names as pointers with a typedef, but if you must, change your malloc statement to

     place=(place_t)malloc(sizeof *place)*num);

Another problem is that you free() the struct and afterwards try to access a member inside it, which is invalid.

free(place);
free(place->name);

You have to do it in this order

free(place->name);
free(place);

You are also leaking memory e.g. here:
for(i=0;iname=(char *)malloc(sizeof(char)*MAX);

What happens the 2. time in this loop ? You assign to place->name , losing the pointer to the memory you allocated in the first iteration of the loop. Maybe you meant to use place[num] inside the loop as you do try to allocate many place_t's in the place=(place_t)malloc(sizeof(place_t)*num); statement.

回复 原文
睡美人的小仙女 2024-12-23 21:02:09

问题不在于 malloc 语句，而在于使用完毕后释放内存的顺序。

例如

free(place);
free(place->name);

应该是

free(place->name);
free(place);

，否则分配给 name 的内存将不会被释放。

同样，调用
免费（地点）；
不会释放分配的内存
place->name=(char *)malloc(sizeof(char)*MAX);

您必须手动释放分配给每个 Malloc 语句的内存。

在通过 malloc 再次使用指向内存位置的指针之前，最好先检查它们是否为 null。

如果它们不是 null，则释放它们，然后将它们设置为 null。这将有助于确保您没有内存泄漏。

The problem isn't so much the malloc statements, but rather the order in which you're freeing the memory up once you're finished with it.

e.g.

free(place);
free(place->name);

should be

free(place->name);
free(place);

otherwise memory allocated to name won't be freed.

Similarly, calling
free(place);
wont free memory allocated in
place->name=(char *)malloc(sizeof(char)*MAX);

You must manually free the memory allocated to each Malloc statement.

It's always best to check whether pointers to memory locations are null before using them again with malloc.

If they're not null then free them and then set them to null. This will help in ensuring that you don't have memory leaks.

回复 原文
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