[C,Java,Python]Command Line Argument: argv, argc, sys.argv, args

JAVA

public class BooksTest
{
    public static void main(String[] args)
    {
        int i;
        for (i = 0; i < args.length; i++)
        {
            System.out.printf("args[%d] = %s
", i, args[i]);
        }
    }
}

编译:

javac BooksTest.java && java BooksTest jerry elaine kramer george

输出结果:

args[0] = jerry
args[1] = elaine
args[2] = kramer
args[3] = george

注意不包含文件名，也就是说：args[0]不是BooksTest，这点与python，C不一样

PYTHON

import sys
if len(sys.argv) > 1:
    print(sys.argv)
    for i in range(len(sys.argv)):
        print(sys.argv[i])
else:
    print((sys.argv))
    print(sys.argv[0])
    # 或者用下面的方式遍历list
    # for item in sys.argv:
    #     print(item)

运行1：

python3 01_sys_argv.py

输出结果：

['01_sys_argv.py']
01_sys_argv.py

运行2：

python3 01_sys_argv.py jerry elaine kramer george

输出结果

['01_sys_argv.py', 'jerry', 'elaine', 'kramer', 'george']
01_sys_argv.py
jerry
elaine
kramer
george

C

argc = argument count

argv = argument vector

#include <stdio.h>
int main(int argc, const char * argv[])
{
    int i;
    for (i = 0; i < argc; i++)
    {
        printf("argv[%d] = %s
", i, argv[i]);
    }
    return 0;
}

编译后运行1:

./a.out

结果：

argv[0] = ./a.out

运行2:

./a.out jerry elaine george kramer

argv[0] = ./a.out
argv[1] = jerry
argv[2] = elaine
argv[3] = george
argv[4] = kramer

  

总结：C有单独的计数器argc,

Pyhton有len(sys.argv)

Java有argv.length