c - Confusion regarding a printf statement -

so running code

#include<stdio.h> int add(int x, int y) { return printf("%*c%*c",x ,' ',y,' ');  } int main() { printf("sum = %d", add(3,4)); return 0; } 

and can't seem understand how following statement works

return printf("%*c%*c",x ,' ',y,' ');   

so tried writing simple code

int x=3; printf("%*c",x); 

and got weird special character (some spaces before it) output

printf("%*c",x,' '); 

i getting no output. have no idea happening? please help. thank you.

this code

int x=3; printf("%*c",x,'a'); 

makes use of minimum character width can set each input parameter printf.

what above print out a character, specifies minimum width x characters - output a character preceded 2 spaces.

the * specifier tells printf width of part of output string formed input parameter x characters minimum width x must passed additional argument prior variable printed. width (if required) formed blank spaces output before variable printed. in case width 3 , output string (excluding quotes there illustrate spaces)

"  a"  

with code here

printf("%*c",x); 

you have passed length value, forgotten pass variable want printed.

so code

return printf("%*c%*c",x ,' ',y,' '); 

is saying print space character minimum width of x characters (with code x = 3), print space character minimum of y characters (in code y = 4).

the result printing out 7 blank space characters. length return value of printf (and hence add function) confirmed output of

sum = 7 

from printf inside main().

if change code

return printf("%*c%*c",x ,'a',y,'b'); 

you see string (obviously excluding quotes)

"     b"  

printed make happening more clear.