main() Function
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int main() //function heading
{
statements
return 0;
}
A function has two parts. One is called function heading. The first word int is call return type, indicating what information will be returned after executing the function. The content in parentheses is called argument list.
The other part is function body, which is enclosed in braces. Function body contains some statements tell what the program to do. Every statement must end with a semicolon.
Main function is a special function that it’s never called by any other part of the program. Sometimes, main function is written as
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int main(int argc, char* argv[])
Arguments argc stands for argument count and argv stands for argument value. argc is the number that arguments input in command line, and argv contains every char array of arguments. for example:
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#include <iostream>
using namespace std;
int main(int argc, char *argv[])
{
cout << "There are " << argc << " arguments" << endl;
for (int i = 0; i < argc; ++i) {
cout << "argument " << i << ": " << argv[i] << endl;
}
return 0;
}
Name it as test.cpp, compile and execute it in command line:
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> g++ test.cpp -o test
> test.exe hello world 1 2 3
There are 6 arguments
argument 0: test.exe
argument 1: hello
argument 2: world
argument 3: 1
argument 4: 2
argument 5: 3
