命令行参数

c语言中命令行参数argc,argv

main(int argc,char argv)argv为指针的指针argc为整数 表示命令行参数的个数

char argv or: char argv[] or: char argv[][]

main()括号内是固定的写法。

下面给出一个例子来理解这两个参数的用法：

假设程序的名称为Command_Line.exe，完整路径名为：C:\Command_Line.exe

当只输入C:\Command_Line.exe 则由操作系统传来的参数为：argc=1,表示只有一程序名称。char argc[]只有一个元素，argv[0]指向输入的程序路径及名称：Command_Line.exe当输入的参数为：

"localhost" "esri_sde" "oradb" "zhangbinglong" "zbl" "default"

则argc = 7；其中：argv[1] = localhost;argv[2] = esri_sde;......argv[6] = default;

使用命令行参数有两种方式：1.项目属性->配置属性->调试->命令参数:输入："localhost" "esri_sde" "oradb" "zhangbinglong" "zbl" "default"可以使用双引号标识， 也可以只保留空格，具体可参见msdn.2.Dos窗口下执行程序：C:\Command_Line.exe "localhost" "esri_sde" "oradb" "zhangbinglong" "zbl" "default"->enter...............................

请注意: 一旦想说明这些参数, 则必须按argc, argv, env 的顺序, 如以下的例子:main()main(int argc)main(int argc, char argv[])main(int argc, char argv[], char env[])其中第二种情况是合法的, 但不常见, 因为在程序中很少有只用argc, 而不用argv[]的情况。以下提供一样例程序EXAMPLE.EXE, 演示如何在main()函数中使用三个参数:1/program name EXAMPLE.EXE/2＃include<stdio.h>

3＃include<stdlib.h>

4

5intmain(intargc,charargv[],char*env[])

6{

7inti;

8printf("These are the %d command- line arguments passed to main:\n\n", argc);

9for(i=0; i<=argc; i++)

10{

11printf("argv[%d]:%s\n", i, argv[i]);

12}

13

14printf("\nThe environment string(s)on this system are:\n\n");

15for(i=0; env[i]!=NULL; i++)

16{

17printf("env[%d]:%s\n", i, env[i]);//C++ Code: cout<< "argv[" << i <<"]" << argv[i] <<endl;

18}

19

20return0;

21

22}

应该提醒的是: 传送main() 函数的命令行参数的最大长度为128 个字符 (包括参数间的空格), 这是由DOS 限制的。

Parsing C++ Command-Line Arguments :

Microsoft C/C++ startup code uses the following rules when interpreting arguments given on the operating system command line:

1.Arguments are delimited by white space, which is either a space or a tab.

2.The caret character (^) is not recognized as an escape character or delimiter. The character is handled completely by the command-line parser in the operating system before being passed to the argv array in the program.

3.A string surrounded by double quotation marks ("string") is interpreted as a single argument, regardless of white space contained within. A quoted string can be embedded in an argument.

4.A double quotation mark preceded by a backslash (\") is interpreted as a literal double quotation mark character (" ).

5.Backslashes are interpreted literally, unless they immediately precede a double quotation mark.

6.If an even number of backslashes is followed by a double quotation mark, one backslash is placed in the argv array for every pair of backslashes, and the double quotation mark is interpreted as a string delimiter.

7.If an odd number of backslashes is followed by a double quotation mark, one backslash is placed in the argv array for every pair of backslashes, and the double quotation mark is "escaped" by the remaining backslash, causing a literal double quotation mark (") to be placed in argv.

Example:The following program demonstrates how command-line arguments are passed://command_line_arguments.cpp

//compile with: /EHsc

#include<iostream>



usingnamespacestd;

intmain(intargc,//Number of strings in array argv

charargv[],//Array of command-line argument strings

charenvp[] )//Array of environment variable strings

{

intcount;



//Display each command-line argument.

cout<<"\nCommand-line arguments:\n";

for( count=0; count<argc; count++)

cout<<"argv["<<count<<"]"

<<argv[count]<<"\n";

}

The following table shows example input and expected output, demonstrating the rules in the preceding list.

Results of Parsing Command LinesCommand-Line Input argv[1] argv[2] argv[3]"abc" d eabcdEa\\b d"e f"g ha\\bde fgH

a\\"b c da\"bcD

a\\"b c" d ea\b cdE原文链接: https://www.cnblogs.com/red_giser/archive/2010/08/23/1806628.html

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