OTHERCriticalRuntime ErrorApril 30, 2026

Runtime Error

undefined reference to `main'

What This Error Means

The linker is unable to find the definition of the `main` function, which is the entry point of a C program.

Why It Happens

This error typically occurs when the compiler is unable to link the object files together, often due to a missing or incorrect library.

How to Fix It

  1. 1Check that the `main` function is defined in one of the source files.
  2. 2Verify that the compiler is correctly linking the object files together.
  3. 3Ensure that the necessary libraries are included in the compilation process.

Example Code Solution

❌ Before (problematic code)
Code
int main() { return 0; }
✅ After (fixed code)
Code
int main() { return 0; } // No changes needed, but ensure this is in a file that is being compiled.

The `main` function must be defined in a file that is being compiled.

Also Related

undefined reference to `printf'undefined reference to `malloc'

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