在 C 中使用 strtok 将日期字符串转换为整数

发布于 2024-12-11 02:47:48 字数 859 浏览 1 评论 0原文

我在使用 strtok() 函数时遇到问题。我输入的日期为 01/01/2000；我的预期产出为：2000 年 1 月 1 日；但我只得到 1, 1, 1。这是为什么？

#include <stdio.h>
#include <stdlib.h>
#include "date.h"
#include <string.h>

struct date{
int day;
int month;
int year;
};

Date *date_create(char *datestr){

printf("inside date_create");
char delim[] = "/";
Date* pointerToDateStructure = malloc(sizeof(Date));
 printf("%s",datestr);
char string[10];
*strcpy(string, datestr);
pointerToDateStructure->day = atoi(strtok( string, delim));
pointerToDateStructure->month = atoi(strtok( string, delim));
pointerToDateStructure->year = atoi(strtok( string, delim));
printf("%d", pointerToDateStructure->day);
printf("%d", pointerToDateStructure->month);
printf("%d", pointerToDateStructure->year);

return pointerToDateStructure;
}

原文

I'm having trouble using the strtok() function. I feed this a date of 01/01/2000; my
expected output is: 1, 1, 2000; however I'm just getting 1, 1, 1.
Why is that?

#include <stdio.h>
#include <stdlib.h>
#include "date.h"
#include <string.h>

struct date{
int day;
int month;
int year;
};

Date *date_create(char *datestr){

printf("inside date_create");
char delim[] = "/";
Date* pointerToDateStructure = malloc(sizeof(Date));
 printf("%s",datestr);
char string[10];
*strcpy(string, datestr);
pointerToDateStructure->day = atoi(strtok( string, delim));
pointerToDateStructure->month = atoi(strtok( string, delim));
pointerToDateStructure->year = atoi(strtok( string, delim));
printf("%d", pointerToDateStructure->day);
printf("%d", pointerToDateStructure->month);
printf("%d", pointerToDateStructure->year);

return pointerToDateStructure;
}

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但可醉心 2024-12-18 02:47:48

首先，您要使用strtol而不是atoi（或sscanf，见下文）。函数atoi 是不安全的。

其次，strtok 需要 NULL 而不是 string：

pointerToDateStructure->day = atoi(strtok( string, delim));
pointerToDateStructure->month = atoi(strtok( NULL, delim)); /* NULL instead of string. */
pointerToDateStructure->year = atoi(strtok( NULL, delim)); /* See above. */

第三，您没有检查 strtok 返回的值。

附带说明一下，您确定 sscanf 无法解析您的数据吗？

sscanf(str, "%d/%d/%d", &day, &month, &year)

编辑 abelenky 的解释：

函数 strtok 有状态。它“记住”它之前正在处理的字符串，如果您传递“NULL”，它会继续处理同一个字符串，从之前停止的地方开始。如果每次传递一个字符串参数，则每次都会从头开始。

First of all, you want to use strtol instead of atoi (or sscanf, see below). The function atoi is unsafe.

Second, strtok needs NULL instead of string:

pointerToDateStructure->day = atoi(strtok( string, delim));
pointerToDateStructure->month = atoi(strtok( NULL, delim)); /* NULL instead of string. */
pointerToDateStructure->year = atoi(strtok( NULL, delim)); /* See above. */

Third, you are not checking the value returned by strtok.

As a side note, are you sure sscanf can't parse your data ?

sscanf(str, "%d/%d/%d", &day, &month, &year)

EDIT Explanation by abelenky:

The function strtok has state. It "remembers" what string it was working on before, and if you pass "NULL", it continues to work on that same string, picking up where it stopped before. If you pass it a string parameter each time, it starts at the beginning each time.

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