Main Function

The main function is the entry point to any Spice program. When the operating system runs your compiled executable, the main function is the first function, which is called. Therefore, it is mandatory and must have the signature int main() or int main(int argc, string[] argv) for retrieving command line arguments. The main function has a return value of type int, which represents the return code / exit code / status code of the executable.

Usage¶

The main function can be declared like this:

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f<int> main() {
    ... // Code to do something
}

Like any other function, the main function automatically declares the variable result of the same type as the function return type. You then have the option to use either the return statement (e.g.: return 1;) or assign a value to the result variable. If you choose the second option, the value of this variable gets returned at the end of the function body. Unlike normal functions, the main function has 0 as the initial value assigned to the result variable for reasons of convenience and to not always have to write return 0; or result = 0; to exit the program with a positive exit code.

Command Line Arguments¶

Spice programs can accept command line arguments similar you would write it in C:

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f<int> main(int argc, string[] argv) {
    printf("Argc: %d\n", argc);
    printf("Argv no. 0: %s\n", argv[0]);
    if (argc > 1) {
        printf("Argv no. 1: %s\n", argv[1]);
    }
}

The parameter argc holds the number of passed arguments and the argv array contains the values of those arguments.