Use the strlen() function provided by the C standard library string.h header file.
char name[7] = "Flavio";
strlen(name);This function will return the length of a string as an integer value.
Working example:
#include <string.h>
#include <stdio.h>
int main(void) {
char name[7] = "Flavio";
int length = strlen(name);
printf("Name length: %u", length);
}Download my free C Handbook