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int main(int argc, const char * argv[])
In the C language learning time，We are writing a program，Then view the results in a terminal run，Enter a number, and so on ...... do not know if you have not tried it allows you to write programs that can accept parameters like system commands it? For example,：ls -al like this。
If you wish to do so，Like above, as to declare it!
among them：
argv： Pointer Pointer
argc： Integer
For chestnuts
The name of the program to test assumptions，When only input test，It came by the operating system parameters：
argc = 1, represents only a program name；
argc only one element，argv[0]Point to Programs Enter the path and name：./ test
When the input test para_1，There is a parameter，It came by the operating system parameters：
argc = 2，In addition to showing the name of the program but also have a parameter；
argv[0]Point to Programs Enter the path and name；
argv[1]Pointing to a string parameter para_1
When the input test para_1 para_2 there are two parameters，It came by the operating system parameters：
argc = 3，In addition to showing the program name outside there are two parameters；
argv[0]Point to Programs Enter the path and name；
argv[1]Pointing to a string parameter para_1；
argv[2]Pointing to a string parameter para_2；
so，So ~
The actual terms of chestnuts：
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int main(int argc, const char * argv[]) |
char *argv[]: argv is an array of pointers，Argc is the number of elements，Stored is a pointer to each parameter，The first element of argv[0]The full path name for the program to run，From the two elements(argv[1])Start，Is the name of each parameter，The final element is NULL。In general，That is,：
* argv: Array of strings
argv[0] The full path name for the program to run
argv[1] The first string is executed after the program name;
argv[2] For the second string after the execution of the program name;
…
argv[argc]Is NULL。
int argc： It indicates the size of the argv，Is the actual number of arguments +1，Where +1 is because argv[0]Is the name of the compiled executable file
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/*program name EXAMPLE.EXE*/ ＃i nclude <stdio.h> ＃i nclude <stdlib.h> main(int argc, char *argv[], char *env[]) { int i; printf( "These are the %d command- line arguments passed to main:\n\n", argc); for( i = 0; i <= argc; i++) printf( "argv[%d]:%s\n", i, argv[i] ); printf( "\nThe environment string(s)on this system are:\n\n"); for( i = 0; env[i] != NULL; i++ ) printf( " env[%d]:%s\n", i, env[i] ); } ./EXAMPLE first "I’m a good boy" c "last " stop //注意: 可以用双引号括起内含空格的参数, 如本例中的: " argument with blanks"和"Last but one")。 //结果是这样的: These are the 6 command-linearguments passed to main: argv[0]:./ EXAMPLE argv[1]:first argv[2]: I’m a good boy argv[3]:c argv[4]: last argv[5]:stop argv[6]:(NULL) |
In this article from referenceHere。
Original article written by LogStudio：R0uter's Blog » c language command-line arguments argc,argv
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