c4

C in four functions

9,633

1,421

9,633

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write-a-C-interpreter

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Write a simple interpreter of C. Inspired by c4 and largely based on it.

Quick Overview

C4 is a minimalist self-hosting C compiler written in C. It's designed to be small, simple, and capable of compiling itself. The entire compiler is contained in a single C file, making it an excellent educational tool for understanding compiler construction.

Pros

Extremely compact (less than 1000 lines of code)
Self-hosting, capable of compiling itself
Educational resource for learning about compilers
Implements a subset of C, making it easier to understand than full C compilers

Cons

Limited feature set compared to full C compilers
Not suitable for production use or compiling complex C programs
Lacks optimizations and advanced features
May not be fully compliant with modern C standards

Code Examples

Basic function definition and call:

int add(int a, int b) {
    return a + b;
}

int main() {
    int result = add(5, 3);
    return result;
}

Simple if-else statement:

int max(int a, int b) {
    if (a > b)
        return a;
    else
        return b;
}

While loop example:

int sum_to_n(int n) {
    int sum = 0;
    int i = 1;
    while (i <= n) {
        sum = sum + i;
        i = i + 1;
    }
    return sum;
}

Getting Started

To use C4, follow these steps:

Clone the repository:

git clone https://github.com/rswier/c4.git

Compile C4 using a C compiler:
```
gcc -o c4 c4.c
```
Use C4 to compile a C file:
```
./c4 your_program.c
```
Run the compiled program:
```
./a.out
```

Note that C4 implements a subset of C, so not all C programs will compile successfully. Refer to the project documentation for supported features and limitations.

Competitor Comparisons

write-a-C-interpreter

4,006

Write a simple interpreter of C. Inspired by c4 and largely based on it.

Pros of write-a-C-interpreter

More comprehensive documentation and explanations
Cleaner code structure with better organization
Includes a more complete set of C language features

Cons of write-a-C-interpreter

Larger codebase, potentially harder to grasp quickly
Less compact and minimalist approach
May be slower to compile due to increased complexity

Code Comparison

c4:

enum { Num = 128, Fun, Sys, Glo, Loc, Id, Char, Else, Enum, If, Int, Return, Sizeof, While, ... };

write-a-C-interpreter:

enum {
    TK_NUM = 128, TK_STR, TK_CHAR,
    TK_ID, TK_COMMENT, TK_KEYWORD,
    TK_INC, TK_DEC, TK_SHL, TK_SHR,
    ...
};

The code comparison shows that write-a-C-interpreter uses more descriptive token names and includes a wider range of language constructs, while c4 opts for a more concise approach.

Both projects aim to create a simple C interpreter, but write-a-C-interpreter focuses on being more educational and feature-complete, while c4 prioritizes minimalism and compactness. The choice between them depends on whether you prefer a more comprehensive learning experience or a quick, bare-bones implementation.

acwj

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A Compiler Writing Journey

Pros of acwj

More comprehensive and educational, covering a wider range of compiler topics
Includes detailed explanations and documentation for each step
Gradually builds a more feature-rich compiler

Cons of acwj

Significantly larger and more complex codebase
Takes longer to work through and understand fully
May be overwhelming for absolute beginners

Code Comparison

c4:

enum { Num = 128, Fun, Sys, Glo, Loc, Id, Char, Else, If, Int, Return, Sizeof, While, };

acwj:

enum {
  T_EOF, T_PLUS, T_MINUS, T_STAR, T_SLASH, T_INTLIT, T_SEMI, T_EQUALS,
  T_LBRACE, T_RBRACE, T_LPAREN, T_RPAREN, T_AMPER, T_LOGAND, T_LOGOR,
  // ... (more tokens)
};

Both projects define enums for tokens, but acwj's enum is more extensive, reflecting its broader scope and more feature-rich compiler implementation.

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README

c4 - C in four functions

An exercise in minimalism.

Try the following:

gcc -o c4 c4.c
./c4 hello.c
./c4 -s hello.c

./c4 c4.c hello.c
./c4 c4.c c4.c hello.c

Top Related Projects

write-a-C-interpreter

4,006

Write a simple interpreter of C. Inspired by c4 and largely based on it.

acwj

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