This C program demonstrates the use of external variable declarations and definitions. External variables a, b, c, and f are declared at the beginning of the program using the extern keyword, indicating they are defined elsewhere. In the main function, these variables are then defined and initialized: a and b are assigned values of 10 and 20, respectively, and c is calculated as their sum. The value of c is printed using printf. A floating-point division is performed, and the result is assigned to f, which is then printed. The program outputs the values of c and f before terminating.
#include"stdio.h"
// Variable declaration:
extern int a, b;
extern int c;
extern float f;
int main () {
/* variable definition: */
int a, b;
int c;
float f;
/* actual initialization */
a = 10;
b = 20;
c = a + b;
printf("value of c : %d \n", c);
f = 70.0/3.0;
printf("value of f : %f \n", f);
return 0;
}value of c : 30
value of f : 23.333334
Press any key to continue . . .
First read the algorithm, then study the program code line by line. After that, compare the code with the output and finally go through the explanation. This approach helps learners understand both the logic and the implementation properly.
After understanding this example, try to rewrite the same program without looking at the code. Then change some values or logic and run it again. This helps improve confidence and keeps learners engaged on the page for longer.