c - 从命令行输入解析字符串，移入数组

Question

我正在尝试获取字符输入，使用非字母字符作为分隔符将它们分解为字符串，并将这些字符串移动到它们自己的数组中。我似乎无法获得该代码块的有效实现，这非常令人沮丧。如有任何帮助，我们将不胜感激。

char *ptr = strtok(arg1, " "); //pointer to the first token delimited by a space.
int i=0;
while (ptr != NULL) { //separate all the tokens and move each into the tokens array
    new_num_tokens++;

    if(new_num_tokens == num_tokens) { //need to allocate more memory
        num_tokens += 2;
        char *tmp = (char *)realloc(tokens, (num_tokens+1) * sizeof(char)); //num_tokens+1 for the null character
        if(!tmp) {
            printf("Could not reallocate memory");
            return EXIT_FAILURE;
        } else {
            tokens = tmp;
        }
    }
    strcpy(&tokens[i], ptr);

    ptr = strtok(NULL, " ");
    i+=sizeof(char);
}

未显示的是迭代整个输入并将所有非字母字符替换为空格的代码。我将 token 数量增加 2，以模拟将数组增加 2。

Answer 1

我通过将 char *tokens 数组转换为双指针 char **tokens 解决了这个问题，如下所述:

    char **tokens = malloc(sizeof(char *) * 2);
    char *p = arg1;
    for(; *p; p++) {
        if (!isalpha(*p)) *p = ' '; //replace every nonalpha character with a space so we can use space
                                    //as a delimiter in strtok()
    }

    char *ptr = strtok(arg1, " "); //pointer to the first token delimited by a space.
    int i=0;
    while (ptr != NULL) { //separate all the tokens and move each into the tokens array
        new_num_tokens++;

        if(new_num_tokens == num_tokens) { //need to allocate more memory
            num_tokens += 2;
            char **tmp = realloc(tokens, (num_tokens+1) * sizeof(char *)); //num_tokens+1 for the null character
            if(!tmp) {
                printf("Could not reallocate memory");
                return EXIT_FAILURE;
            } else {
                tokens = tmp;
            }
        }
        tokens[i] = ptr;

        ptr = strtok(NULL, " ");
        i++;
    }