c - Strtok 使用动态内存

Question

我有以下代码，我需要帮助获取和存储最后一个 token 。现在代码在每个空格后标记化，但是当它到达我的文本文件的末尾时，它不会标记最后一个值。我很确定我需要在 malloc 语句之前拥有 token ，但是当我在前面添加它时，我遇到了段错误。有人知道这个问题吗？由于 realloc 而初始化了上面的 myStruct.extras = NULL；它是一个 char **。

token = strtok(fileArrayPTR[p],"X");
while (token!= NULL)
{   

    if (tempCounter == 0)
    { 
        token = strtok(NULL," "); 
        myStruct.dimensions[1] = strtol(token,&ptr,10);
    }else{
        myStruct.extras = realloc(myStruct.extras,(extraCounter + 1) * sizeof(char *)); 
        myStruct.extras[extraCounter] = malloc(strlen(token)+1);  
        strcpy(myStruct.extras[extraCounter],token);
        token = strtok(NULL," ");
        extraCounter++;
    }
}

编辑:忘了放递增的计数器

Answer 1

这是问题的(第二个版本)代码:

token = strtok(fileArrayPTR[p],"X");
while (token!= NULL)
{   
    if (tempCounter == 0)
    { 
        token = strtok(NULL," "); 
        myStruct.dimensions[1] = strtol(token,&ptr,10);
    }else{
        myStruct.extras = realloc(myStruct.extras,(extraCounter + 1) * sizeof(char *)); 
        myStruct.extras[extraCounter] = malloc(strlen(token)+1);  
        strcpy(myStruct.extras[extraCounter],token);
        token = strtok(NULL," ");
        extraCounter++;
    }
}

这不是一个独立的程序。我们可以通过以下方式改进它:

• 删除结构。
• 显示相应的变量声明。
• 将其转换为简单的 main()。

这些变化导致:

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

int main(void)
{
    int extraCounter = 0;
    char **extras = 0;
    int tempCounter = 0;
    char *ptr = 0;
    char data[] = "10X16 something another-thing";
    char *token = strtok(data, "X");
    int dimension1 = strtol(token, &ptr, 10);
    int dimension2 = -1;
    while (token!= NULL)
    {   
        if (tempCounter == 0)
        {
            token = strtok(NULL," "); 
            dimension2 = strtol(token, &ptr, 10);
            tempCounter++;
        }
        else
        {
            extras = realloc(extras, (extraCounter + 1) * sizeof(char *)); 
            extras[extraCounter] = malloc(strlen(token)+1);  
            strcpy(extras[extraCounter], token);
            token = strtok(NULL, " ");
            extraCounter++;
        }
    }

    printf("Dimensions: %dx%d\n", dimension1, dimension2);
    for (int i = 0; i < extraCounter; i++)
        printf("%d: [[%s]]\n", i, extras[i]);

    return 0;
}

运行时，它会产生:

Dimensions: 10x16
0: [[16]]
1: [[something]]
2: [[another-thing]]

代码有问题吗？是的，dimension2 的代码不会重新调用 strtok()，因此 16 被处理了两次，一次作为维度，一次作为字符串。可能不是想要的。因此:

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

int main(void)
{
    int extraCounter = 0;
    char **extras = 0;
    int tempCounter = 0;
    char *ptr = 0;
    char data[] = "10X16 something another-thing";
    char *token = strtok(data, "X");
    int dimension1 = strtol(token, &ptr, 10);
    int dimension2 = -1;
    while (token !=  NULL)
    {
        if (tempCounter == 0)
        {
            token = strtok(NULL, " ");
            dimension2 = strtol(token, &ptr, 10);
            tempCounter++;
        }
        else
        {
            extras = realloc(extras, (extraCounter + 1) * sizeof(char *));
            extras[extraCounter] = malloc(strlen(token) + 1);
            strcpy(extras[extraCounter++], token);
        }
        token = strtok(NULL, " ");
    }

    printf("Dimensions: %dx%d\n", dimension1, dimension2);
    for (int i = 0; i < extraCounter; i++)
        printf("%d: [[%s]]\n", i, extras[i]);

    return 0;
}

编译:

gcc -g -O3 -std=c11 -Wall -Wextra -Wmissing-prototypes -Wstrict-prototypes -Werror ss.c -o ss

输出:

Dimensions: 10x16
0: [[something]]
1: [[another-thing]]

看起来更好...