为什么从此结构打印会出现分段错误?
我试图创建一个 Product 结构数组,然后打印数组中每个 Product 的名称和代码,但我不断收到分段错误。我尝试在没有循环的情况下插入每个值,然后打印,它可以工作,但我想自动化它。函数 fill_products 根据用户的输入填充产品数组,而 select_products 则打印整个数组的每个名称-代码对。
这是我的代码:
#include <stdio.h>
#include <stdlib.h>
typedef struct
{
int code;
char *name;
float price;
} Product;
void select_products(Product *products, int len)
{
int i;
printf("%-30s%s\n", "Name", "Code");
for (i = 0; i < len; i++)
{
printf("%-30s%d\n", products[i].name, products[i].code);
}
return;
}
void fill_products(Product *products, int len)
{
int i, code;
char *name;
float price;
for (i = 0; i < len; i++)
{
printf("Insert product name (%d / %d): ", i + 1, len);
scanf("%s", &name);
printf("Insert product price (%d / %d): ", i + 1, len);
scanf("%f", &price);
products[i].code = i;
products[i].name = name;
products[i].price = price;
}
return;
}
int is_alloc(Product *products)
{
if (products == NULL)
{
printf("Error: memory allocation unsuccessful.\n");
}
return products != NULL;
}
int main(void)
{
int len, n_bytes;
Product *products;
printf("Insert length of array: ");
scanf("%d", &len);
n_bytes = sizeof *products * len;
products = malloc(n_bytes);
if(!is_alloc(products))
{
exit(0);
}
fill_products(products, len);
select_products(products, len);
free(products);
return 0;
}
I'm trying to create an array of Product structs and then print the name and code of each Product in the array, but I keep getting a segmentation fault. I have tried to insert each value without a loop and then printing, and it works, but I'd like to automate it. The function fill_products fills the products array according to the user's input, and the select_products prints each name-code pair for the entire array.
This is my code:
#include <stdio.h>
#include <stdlib.h>
typedef struct
{
int code;
char *name;
float price;
} Product;
void select_products(Product *products, int len)
{
int i;
printf("%-30s%s\n", "Name", "Code");
for (i = 0; i < len; i++)
{
printf("%-30s%d\n", products[i].name, products[i].code);
}
return;
}
void fill_products(Product *products, int len)
{
int i, code;
char *name;
float price;
for (i = 0; i < len; i++)
{
printf("Insert product name (%d / %d): ", i + 1, len);
scanf("%s", &name);
printf("Insert product price (%d / %d): ", i + 1, len);
scanf("%f", &price);
products[i].code = i;
products[i].name = name;
products[i].price = price;
}
return;
}
int is_alloc(Product *products)
{
if (products == NULL)
{
printf("Error: memory allocation unsuccessful.\n");
}
return products != NULL;
}
int main(void)
{
int len, n_bytes;
Product *products;
printf("Insert length of array: ");
scanf("%d", &len);
n_bytes = sizeof *products * len;
products = malloc(n_bytes);
if(!is_alloc(products))
{
exit(0);
}
fill_products(products, len);
select_products(products, len);
free(products);
return 0;
}
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请启用编译器警告,并注意它们。
这段代码
是假的,根本不符合您的预期。
您必须单独为
name
分配空间(然后不要忘记free()
它),或者使该空间在name
中可用。 >Product 结构如下:(假设
name
长度有合理的限制)。Please enable compiler warnings, and pay attention to them.
This code:
is bogus and doesn't do at all what you intend.
You must either allocate space for
name
separately (and then not forget tofree()
it), or make that space available in theProduct
structure like so:(this assumes there is a reasonable limit on
name
length).