C + + in the Find function, strstr,strcmp the difference. __ function

Find is a function in the C + + string class. The value returned is the position that the substring appears in the lookup string, and returns 1 if it is not found.

He and Strstr are different, strstr look for substrings from a string.
The first argument is the address of the string to look for, and the second is the address of the lookup substring.
Returns the first-character address of the substring of the string to find. Returns a null pointer if the substring does not exist.

strcmp (S1,S2) compares two strings S1 and S2 are the same. If S1 equals S2, return 0;