C / C++中的strcspn()函数

C / C++中的strcspn()函数将两个字符串作为输入，即string_1和string_2作为其参数，并通过遍历string_2中存在的任何字符来搜索string_1。如果在string_1中找不到string_2的任何字符，则该函数将返回string_1的长度。此函数在cstring头文件中定义。

句法 ：

size_t strcspn ( const char *string_1, const char *string_2 ) 

参数：该函数接受两个强制性参数，如下所述：

• string_1：指定要搜索的字符串
• string_2：指定包含要匹配字符的字符串

返回值：该函数返回字符之前任何从STRING_2匹配字符的STRING_1中走过的数量。

下面的程序说明了上述函数：

程序1：

// C++ program to illustrate the
// strcspn() function
#include 
using namespace std;
  
int main()
{
    // String to be travered
    char string_1[] = "geekforgeeks456";
  
    // Search these characters in string_1
    char string_2[] = "123456789";
  
    // function strcspn() traverse the string_1
    // and search the characters of string_2
    size_t match = strcspn(string_1, string_2);
  
    // if matched return the position number
    if (match < strlen(string_1))
        cout << "The number of characters before"
             << "the matched character are " << match;
  
    else
        cout << string_1 << 
        " didn't matched any character from string_2 ";
    return 0;
}

输出：

The number of characters beforethe matched character are 12

程式2：

// C++ program to illustrate the
// strcspn() function When the string
// containing the character to be
// matched is empty
#include 
using namespace std;
  
int main()
{
    // String to be travered
    char string_1[] = "geekforgeeks456";
  
    // Search these characters in string_1
    char string_2[] = ""; // Empty
  
    // function strcspn() traverse the string_1
    // and search the characters of string_2
    size_t match = strcspn(string_1, string_2);
  
    // if matched return the position number
    if (match < strlen(string_1))
        cout << "The number of character before"
             << "the matched character are " << match;
    else
        cout << string_1 << 
        " didn't matched any character from string_2  ";
    return 0;
}

输出：

geekforgeeks456 didn't matched any character from string_2

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