strtok函数源码

以下是一个简化版的strtok函数的源码实现：

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

char *strtok(char *str, const char *delim) {
    static char *nextToken = NULL;  // 保存下一个分割的位置
    if (str != NULL) {
        nextToken = str;
    }
    
    // 如果没有字符串需要分割，直接返回NULL
    if (nextToken == NULL || *nextToken == '\0') {
        return NULL;
    }
    
    // 跳过分隔符
    while (*nextToken != '\0' && strchr(delim, *nextToken) != NULL) {
        nextToken++;
    }
    
    // 找到下一个分隔符的位置
    char *start = nextToken;
    while (*nextToken != '\0' && strchr(delim, *nextToken) == NULL) {
        nextToken++;
    }
    
    // 替换分隔符为字符串结束符，并返回子字符串指针
    if (*nextToken != '\0') {
        *nextToken = '\0';
        nextToken++;
        return start;
    }
    
    return start;
}

int main() {
    char str[] = "Hello, World! This is a test string.";
    const char delim[] = " ,.!";  // 分隔符
    char *token = strtok(str, delim);
    
    while (token != NULL) {
        printf("%s\n", token);
        token = strtok(NULL, delim);
    }
    
    return 0;
}

以上代码将字符串"Hello, World! This is a test string."按照空格、逗号和句号进行分割，并