C Program Structure

In Python you'd do something like this:

python3 slow_program.py

The Python interpreter then executes that file top-to-bottom. If you have a print() at the top level, then it will print something.

The entire file is interpreted line by line, but that's not how C works.

Simplest C Program

The simplest C program is essentially:

int main() {
  return 0;
}

But a lot is happening here...

• A function named main is always the entry point to a C program (unlike Python, which enters at the top of the file).

• int is the return type of the function and is short for "integer". Because this is the main function, the return value is the exit code of the program. 0 means success, anything else means failure.

  • You'll find a lot of abbreviations in C because 1) programmers are lazy, and 2) it used to matter how many bytes your source code was.

• The opening bracket, { is the start of the function's body (C ignores whitespace, so indentation is just for style, not for syntax)

• return 0 returns the 0 value (an integer) from the function. Again, this is the exit code because it's the main function.

  • 0 represents "nothing bad happened" as a return value.

• The pesky ; at the end of return 0; is required in C to terminate statements.

• The closing bracket, } denotes the end of the function's body.

Print

It feels very different coming from Python, but printing in C is done with a function called printf from the stdio.h (standard input/output) library with a lot of weird formatting rules. To use it, you need an #include at the top of your file:

#include <stdio.h>

Then you can use printf from inside a function:

printf("Hello, World!\n");

Write and execute c

Escirbir un archivo en c que imprime "Hola Mundo", compilalo y correlo

#include <stdio.h>

int main() {
  printf("Hello, World!\n");
  return 0;
}