Character string search (start position of specified character)
char *strchr(const char *s, int c);
Returns a pointer indicating the character that has been found. If c does not appear in this character string, the null pointer is returned.
This function obtains the position at which a character the same as c converted into char type appears in the character string indicated by s. The null character (\0) indicating termination is regarded as part of this character string.