For example, having the following code my intention is to operate to obtain an index number
#include <stdio.h>
#include <string.h>
int main(void) {
char mes[2]= {"02"};
int numero;
numero = (int)mes;
char *strings[]={ "Ene", "Feb", "Mar", "Abr", "May", "Jun","Jul", "Ago", "Sep","Oct", "Nov", "Dic"};
printf("%s\n", strings[numero - 1]);
return 0;
}
in the example you should print Feb
Well, use the function atoi( ) (of <stdlib.h> ), which is responsible for precisely that: interprets the content of a string and returns a int .
However, you have to modify your code, since atoi( ) expects a string ending in 0 :
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int main( void ) {
char *mes= "02"; // <-- Cambiamos esto.
int numero;
numero = atoi( mes );
char *strings[]={ "Ene", "Feb", "Mar", "Abr", "May", "Jun","Jul", "Ago", "Sep","Oct", "Nov", "Dic"};
printf( "%s\n", strings[numero - 1] );
return 0;
}
Compiling and executing it, we obtain the desired output:
Feb
This function is not the secure , since we can not check for possible errors ; for example,
atoi( "aa" );
We would return a 0 .
You have similar but more powerful features, such as strtol( ) and strtoll( ) , with return values long int and long long int respectively, with support for different numerical bases and that allow us to detect errors during the interpretation.