gcc -o / -O option flags
gcc -o writes the build output to an output file.
gcc -O sets the compiler's optimization level.
gcc -o option flag
Write the build output to an output file.
Syntax
$ gcc [options] [source files] [object files] -o output file
Example
myfile.c:
// myfile.c
#include <stdio.h>
void main()
{
printf("Program run\n");
}
Build myfile.c on terminal and run the output file myfile:
$ gcc myfile.c -o myfile
$ ./myfile
Program run
$
gcc -O option flag
Set the compiler's optimization level.
option optimization level execution time code size memory usage compile time -O0 optimization for compilation time (default) + + - - -O1 or -O optimization for code size and execution time - - + + -O2 optimization more for code size and execution time -- + ++ -O3 optimization more for code size and execution time --- + +++ -Os optimization for code size -- ++ -Ofast O3 with fast none accurate math calculations --- + +++ +increase ++increase more +++increase even more -reduce --reduce more ---reduce even more
Syntax
$ gcc -Olevel [options] [source files] [object files] [-o output file]
Example
myfile.c:
// myfile.c
#include <stdio.h>
void main()
{
printf("Program run\n");
}
Build myfile.c on terminal and run the output file myfile:
$ gcc -O myfile.c -o myfile
$ ./myfile
Program run
$
See also
Online Reference & Tools