multiple diffinition of " main "

im new to C programming, below is the program that i copy from a website.i get error multiple diffinition of " main " when i click “build”.

#include <stdio.h>

int main()
float num1, num2;
char operation;
while (1) {
scanf("%f%c%f", &num1, &operation, &num2);
if (operation == ‘+’)
printf("%f\n", num1+num2);
if (operation == ‘-’)
printf("%f\n", num1-num2);
if (operation == ‘*’)
printf("%f\n", num1*num2);
if (operation == ‘/’)
printf("%f\n", num1/num2);
return 0;

this forum is for discussing openFrameworks, not C. i encourage you to find a good C forum to get answers about C. here’s one

that said, the problem isn’t with the code you posted but the way you’re compiling and linking it/other files you’re including in the build.