How to determine whether a String string contains a string or not?

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C language style

In C, strings are stored as arrays of characters ending in '\0'.

In C's interface, there is the strstr function, which looks up another string in a string.

char * strstr(const char *str1, const char *str2);

The function is to find str2 in str1, if it exists, then return the starting pointer found, otherwise return NULL.

Reference Code:

#include #include #include using namespace std;int main(){ string a= "abcdefghigklmn" ; char *b= "def" ; char *c= "123" ; if ( strstr (a.c_str(), b) == NULL) //Find b in a, if it does not exist, cout