Calling a function in printf in C? - c

Question

I am a beginner in C programming.
I was writing a simple program to calculate average.
Here is my code:
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
int main()
{
int n, s = 0, num, i;
float avg;
printf("Enter value of total no\n");
scanf("%d", &n);
for (i=1; i<=n; i++)
{
void pri(int i){
switch(i){
case 1:
printf("st");
break;
case 2:
printf("nd");
break;
case 3:
printf("rd");
break;
default:
printf("th");
break;
}
}
printf("Enter %d pri(i) number\n", i);
scanf("%d", &num);
s += num;
}
avg = s / n;
printf("The average is %f",avg);
return 0;
}
But pri(i) is not working as I expected. But later I found another way to do this, so here is the second version of this code:
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
int main()
{
int n, s = 0, num, i;
float avg;
printf("Enter value of total no\n");
scanf("%d",&n);
for (i=1; i<=n; i++)
{
void pri(int i){
switch(i){
case 1:
printf("enter 1st number\n");
break;
case 2:
printf("enter 2nd number\n");
break;
case 3:
printf("enter 3rd number\n");
break;
default:
printf("enter %dth number\n",i);
break;
}
}
pri(i);
scanf("%d", &num);
s += num;
}
avg = s / n;
printf("the average is %f",avg);
return 0;
}
I want to get the results of this second piece of code from the first version.
Can I call functions in printf which are defined somewhere in program?

Answer 1

You cannot tell printf() to call another function in the middle of its execution. printf() expects to receive a formatting string and arguments to replace parts of this string. What you're trying to do (embed a function call in the formatting string) is not possible for a number of reasons.
What you can do is return the string instead of printing it and use it as argument.
const char *pri(int i) {
switch(i) {
case 1:
return "st";
case 2:
return "nd";
case 3:
return "rd";
default:
return "th";
}
}
printf("enter %d%s number\n", i, pri(i));
C doesn't support nested functions (function defined inside another function). Your code works because your compiler adds support for such functions as an extension. In general, you should probably avoid nesting functions.