How to transform all the negative values into positive values using abs() function.

 #include <stdio.h>

#include <stdlib.h>

#include <ctype.h>

#include <string.h>

#include <math.h>

int main()

{

    int year1,year2,age;

    printf("Enter a year : \n");

    scanf("%d",&year1);

    printf("Enter a year : \n");

    scanf("%d",&year2);

    age = year1 - year2;

    printf("%d \n",age);

    age = abs(age);

    printf("%d \n",age);

    return 0;

}