Should I use printf("\n") or putchar('\n') to print a newline in C? [closed]

Question

When I'm writing a program in C, I often have to print a newline by itself. I know you can do this in at least two ways: printf("\n") and putchar('\n'), but I'm not sure which way is the best choice in terms of style and possibly efficiency. Are there any best practices for using one over the other? Does it really matter?

Answer 1

It will make no difference which one you chose if you're using a modern compiler^[1]. Take for example the following C code.

#include <stdlib.h> #include <stdio.h>  void foo(void) {     putchar('\n'); }  void bar(void) {     printf("\n"); } 

When compiled with gcc -O1 (optimizations enabled), we get the following (identical) machine code in both foo and bar:

movl    $10, %edi popq    %rbp jmp _putchar                ## TAILCALL 

Both foo and bar end up calling putchar('\n'). In other words, modern C compilers are smart enough to optimize printf calls very efficiently. Just use whichever one you think is more clear and readable.

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1. I do not consider MS's cl to be a modern compiler.

Answer 2

Are there any best practices for using one over the other?

Let style drives the decision.

Since efficiency of execution is the same or nearly identical, use the style that best conveys the larger code's function.

If the function had lots of printf(), stay with printf("\n").

Likewise for putchar('\n') and puts("")