C Programming - Library Functions - Discussion
#include<stdio.h>
int main()
{
int i;
char c;
for(i=1; i<=5; i++)
{
scanf("%c", &c); /* given input is 'a' */
printf("%c", c);
ungetc(c, stdin);
}
return 0;
}
for(i=1; i<=5; i++) Here the for loop runs 5 times.
Loop 1:
scanf("%c", &c); Here we give 'a' as input.
printf("%c", c); prints the character 'a' which is given in the previous "scanf()" statement.
ungetc(c, stdin); "ungetc()" function pushes character 'a' back into input stream.
Loop 2:
Here the scanf("%c", &c); get the input from "stdin" because of "ungetc" function.
printf("%c", c); Now variable c = 'a'. So it prints the character 'a'.
ungetc(c, stdin); "ungetc()" function pushes character 'a' back into input stream.
This above process will be repeated in Loop 3, Loop 4, Loop 5.