Is for(;;) Faster Than while(1) in C? A Practical Comparison

Test programs

Three minimal C programs that print an infinite‑loop message using different constructs.

#include <stdio.h>
int main() {
    for(;;)
        printf("This is a loop
");
    return 0;
}

#include <stdio.h>
int main() {
    while(1)
        printf("This is a loop
");
    return 0;
}

#include <stdio.h>
int main() {
    start:
        printf("This is a loop
");
        goto start;
    return 0;
}

Generated assembly

Each source file was compiled with gcc -S file.c using GCC 7.5.0 on Ubuntu 18.04. The produced assembly for all three programs is identical, illustrating that the three loop forms generate the same low‑level code.

.file "for.c"
.text
.section .rodata
.LC0:
    .string "This is a loop"
.text
.globl main
.type main, @function
main:
.LFB0:
    .cfi_startproc
    pushq %rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    movq %rsp, %rbp
    .cfi_def_cfa_register 6
.L2:
    leaq .LC0(%rip), %rdi
    call puts@PLT
    jmp .L2
    .cfi_endproc
.LFE0:
    .size main, .-main
    .ident "GCC: (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0"
    .section .note.GNU-stack,"",@progbits

Compiler version

gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0

Additional observations

The same assembly is produced by the Keil IDE, confirming that the loop forms are equivalent across toolchains.

Some compilers issue a warning for while(1) because the constant 1 may be flagged by strict warning settings; for(;;) contains no explicit condition and therefore avoids that warning.

Conclusion

Both for(;;) and while(1) implement an infinite loop with no measurable performance difference; the generated assembly is identical. The choice can be based on readability or compiler‑warning preferences, with for(;;) often considered slightly more elegant.