#include<stdio.h>
void exchange(void);
int a, b; /* declaration of global variables */
int main()
{ /* main program starts here...*/
a = 5;
b = 7;
printf(" In main: a = %d, b = %d\n", a, b);
exchange(); /* function call, no parameters are passed */
printf("\n Back in main: ");
printf("a = %d, b = %d\n", a, b);
return 0;
} /* main program ends here */
void exchange(void)
{ /* function body starts here...*/
int temp; /* decl. of local variable in function*/
printf("\n In function exchange() before change: just received from\
main... a=%d and b=%d",a,b);
temp = a;
a = b;
b = temp; /* interchange over */
printf("\n In function exchange() after change: ");
printf("a = %d, b = %d\n", a, b);
} /* function body ends here*/
In main: a = 5, b = 7
In function exchange() before change: just received from main... a=5 and
b=7
In function exchange() after change: a = 7, b = 5
Back in main: a = 7, b = 5
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.