Let’s work through the common fixes for this make error—this usually stems from simple issues with your working directory, file names, or missing project files. Here’s what to check step by step:

1. Confirm you’re in the correct directory #

First, make sure you’re actually inside the population project folder. Run this command to see your current path:

pwd

You should see something like ~/cs50/pset1/population (or the equivalent path in your CS50 environment). If not, use the cd command to navigate to the right folder. For example:

cd ~/cs50/pset1/population

2. Check that required files exist #

List all files in the directory to verify you have the necessary components:

ls

You should see both population.c (your source code file) and a Makefile (the file that tells make how to compile your program). If population.c is missing, you either haven’t created it yet or saved it in the wrong location. If the Makefile is missing, CS50’s online environment usually generates this automatically—try reloading your workspace or re-downloading the Problem Set 1 files.

3. Double-check your source file name #

The make command is case-sensitive and looks for a .c file that matches the target name exactly. If your file is named Population.c (with a capital P) or has a typo like populatoin.c, make won’t recognize it. Rename it to all lowercase population.c if needed:

mv Population.c population.c

4. Try compiling directly with gcc #

If make still fails, bypass it and compile manually with this command (this also helps confirm your code is syntactically valid):

gcc -o population population.c -lcs50

If this works, your source code is fine, and the issue is likely with the Makefile. If it doesn’t work, you’ll get a specific error pointing to code problems—fix those first, then try make again.

5. Reset your CS50 environment (for online workspaces) #

If you’re using CS50’s Codespace or IDE, sometimes the environment can get out of sync. Try restarting your workspace, or re-cloning the Problem Set repository to get fresh copies of all project files.

内容的提问来源于stack exchange，提问作者Ariful Islam