C Sandbox

C Sandbox - Run C Code Online Free

A powerful online C sandbox that runs C code in your browser using GCC compiler. No installation required, perfect for learning C, testing code snippets, debugging, and quick prototyping. Supports C11 standard with full compiler options.

What is C Sandbox?

C Sandbox is an online C compiler that allows you to run C code directly in your browser without installing anything. Using the Piston API and GCC compiler, it provides:

- Instant code compilation and execution
- Support for standard C library
- Custom compiler flags and arguments
- Standard input (stdin) support
- Error messages and debugging info
- Code examples to learn from

Perfect for students, developers, and anyone learning C programming.

How do I use this C Sandbox?

Using the C Sandbox is simple:

1. Write or paste your C code in the editor
2. (Optional) Add compiler arguments like -Wall -O2
3. (Optional) Provide stdin input if your program needs it
4. Click 'Run Code' to compile and execute
5. View the output or compilation errors
6. Try example codes to learn C basics

You can also download your code as a .c file for later use.

What C features are supported?

The sandbox supports full C programming language features:

- All C11 standard features
- Standard library (stdio.h, stdlib.h, string.h, math.h, etc.)
- Dynamic memory allocation (malloc, calloc, free)
- File I/O operations
- Pointers and pointer arithmetic
- Structures and unions
- Arrays and strings
- Function pointers
- Preprocessor directives

Compiler: GCC 10.2.0 with C11 standard support.

Can I use compiler flags?

Yes! You can add custom compiler arguments in the 'Compiler Arguments' field. Common examples:

- `-Wall` - Enable all warnings
- `-Wextra` - Enable extra warnings
- `-O2` - Optimization level 2
- `-std=c11` - Use C11 standard
- `-lm` - Link math library
- `-g` - Include debugging symbols

Example: `-Wall -Wextra -O2 -std=c11`

How does stdin input work?

If your program uses scanf(), gets(), fgets(), or other input functions, you can provide the input in the 'Standard Input' field.

Example program:
```c
#include <stdio.h>
int main() {
int num;
scanf("%d", &num);
printf("You entered: %d\n", num);
return 0;
}
```

In the stdin field, enter: `42`

The program will read this value and output: `You entered: 42`

Is my code safe and private?

Your code privacy depends on the execution method:

- Code is sent to Piston API (emkc.org) for compilation
- Piston is open-source and maintained by the community
- Code is not stored or logged by Piston
- Execution happens in isolated containers
- No access to your local system

For maximum privacy, you can self-host Piston using Docker.

Key Features

• Run C code online with GCC compiler
• No installation or signup required
• Instant compilation and execution
• Full C11 standard support
• Custom compiler flags and arguments
• Standard input (stdin) support
• Clear error messages and line numbers
• Code examples for learning
• Download code as .c file
• Execution time tracking
• Dark mode support
• Mobile-friendly responsive design
• Free forever - powered by Piston API
• Open source and community-driven