什么是用C来替换字符串函数？ [英] What is the function to replace string in C?

问题描述

给定一个（的char *）的字符串，我想找到一个子都发生并用另外的字符串替换它。我看不出有什么简单的函数实现这种上述＆lt;＆string.h中GT;

Given a (char *) string, I want to find all occurrence of a substring and replace it with an alternate string. I do not see any simple function that achieves this in <string.h>

推荐答案

优化应消除大部分的局部变量。 tmp的指针是有确保的strcpy没有走串找到空。 TMP指向结果每次通话后结束。 （请参见 Shlemiel为什么strcpy的，可恼人的画家算法。）

The optimizer should eliminate most of the local variables. The tmp pointer is there to make sure strcpy doesn't have to walk the string to find the null. tmp points to the end of result after each call. (See Shlemiel the painter's algorithm for why strcpy can be annoying.)

编辑：没有注意到查找所有的第一次：

didn't notice the "find all occurrences" the first time:

// You must free the result if result is non-NULL.
char *str_replace(char *orig, char *rep, char *with) {
    char *result; // the return string
    char *ins;    // the next insert point
    char *tmp;    // varies
    int len_rep;  // length of rep
    int len_with; // length of with
    int len_front; // distance between rep and end of last rep
    int count;    // number of replacements

    if (!orig)
        return NULL;
    if (!rep)
        rep = "";
    len_rep = strlen(rep);
    if (!with)
        with = "";
    len_with = strlen(with);

    ins = orig;
    for (count = 0; tmp = strstr(ins, rep); ++count) {
        ins = tmp + len_rep;
    }

    // first time through the loop, all the variable are set correctly
    // from here on,
    //    tmp points to the end of the result string
    //    ins points to the next occurrence of rep in orig
    //    orig points to the remainder of orig after "end of rep"
    tmp = result = malloc(strlen(orig) + (len_with - len_rep) * count + 1);

    if (!result)
        return NULL;

    while (count--) {
        ins = strstr(orig, rep);
        len_front = ins - orig;
        tmp = strncpy(tmp, orig, len_front) + len_front;
        tmp = strcpy(tmp, with) + len_with;
        orig += len_front + len_rep; // move to next "end of rep"
    }
    strcpy(tmp, orig);
    return result;
}

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