C round function is throwing error: "undefined reference to `round'..." [duplicate]

Question

I hope someone can help me. I am working through CS50x and am working on Pset1 - greedy. I am getting the following error whenever I compile my code:

/tmp/greedy-46be96.o: In function `main':
greedy.c:(.text+0x95): undefined reference to `round'
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Any help will be greatly appreciated. I apologise if the question is vague, I have tried to be in depth. I have used man round in the terminal, and have searched everywhere, trying different solutions, but nothing has worked.

#include <stdio.h>
#include <cs50.h>
#include <math.h>

int main(void)
{
    float owed;
    float change;
    float quarter = 0.25;
    float dime = 0.10;
    float nickel = 0.05;
    float penny = 0.01;

    do {
        printf("How much change is owed?: ");
        owed = GetFloat();

    } while(owed <= 0);

    change = round(owed * 100);
}

I am using this command to compile my code:

clang -o greedy greedy.c -lcs50

Circular

I think you missed to link to math library (add -lm in linker option, at the end) – Coupon

Link the math library. In GCC -lm. – Equites

Hint: This is not a compilation error but a linking error. Can you please paste the command you use to compile/link the code? – Steiger

I agree with purplepsycho. To verify, would you please edit your question to show the exact command line you are using to compile your code? By the way, welcome to the site! Check out the tour for more about asking questions that will attract quality answers. – Cloyd

I apologise if this is a duplicate. I am very new to programming and didn't know what to search for. Thank you for all of your replies :) – Circular

Sorry to be a pain in the arse. What command am I adding "-lm" to? – Circular

Answer 1

The following should work when you compile:

clang -o greedy greedy.c -lcs50 -lm

This links the math library for the compiler.

Wellbred