# C `strspn()`函數 > 原文： [https://beginnersbook.com/2017/11/c-strspn-function/](https://beginnersbook.com/2017/11/c-strspn-function/) **函數`strspn()`**在給定字符串中搜索指定的字符串，并返回給定字符串中匹配的字符數。 ## C `strspn()`聲明 ```c size_t strspn(const char *str1, const char *str2) ``` `str1` - 搜索字符串`str2`的字符的字符串。 `str2` - 另一個字符串，在`str1`中搜索該字符串的字符。 ## `strspn()`的返回值 它返回給定字符串中匹配的字符數。 ## 示例：`strspn()`函數 ```c #include <stdio.h> #include <string.h> int main () { int len; const char str1[] = "abcdefgh"; const char str2[] = "abXXcdeZZh"; /* Searching the string str2 in the string str1. * It returns the count of characters of str2 that * are matched in the str1 */ len = strspn(str1, str2); printf("Number of matched characters: %d\n", len ); return 0; } ``` 輸出： ```c Number of matched characters: 5 ``` #### 相關文章： 1. [C - `strrchr()`函數](https://beginnersbook.com/2017/11/c-strrchr-function/) 2. [C - `strncpy()`函數](https://beginnersbook.com/2017/11/c-strncpy-function/) 3. [C - `strcoll()`函數](https://beginnersbook.com/2017/11/c-strcoll-function/) 4. [C - `strcmp()`函數](https://beginnersbook.com/2017/11/c-strcmp-function/)