On the parameters of main function in C language

Preface ： This is the first time that the author has written a technical article , The format may not be very beautiful , Please bear with me . The main environment used is Linux, Because the author is learning embedded .

1,main Function prototype and the meaning of parameters

Prototype ：

For us beginners , People don't care much about it main The function prototype , Just know the function usage , So they are basically written as

int main() perhaps void main; However main The function also has two very important arguments ; Its function prototype is ：

int main(int argc,char *argv[]);

significance ：

among ,argc It's a int The variable of type represents under standard input （ Command line ）, Number of parameters entered ;argv It's a char Pointer array of type , It stores standard input （ Command line ） Input parameter string .

2, Example

Compared with boring words , Example is the best proof

vi egmain.c  			//linux in vi Editor commands , It means to create a .c file , The file named egmain

/*egmain The content of */
#include <stdio.h>

int main(int argc,char *argv[])
{
    printf("argc The number of %d\n",argc);
    printf("argv[0] For the %s\n",argv[0]);
    printf("argv[1] For the %s\n",argv[1]);
    printf("argv[2] For the %s\n",argv[2]);
    
    return 0; 
}

result ：

gcc egmain.c 			//gcc Compiler gcc The order of , It means to compile egmain, The executable file generated by default without parameters is named             
                          a.out
./a.out hello world   	// To run an executable program 

From the results

Under standard input , Take the space as the separator ,main The function will also ./a.out As input , therefore argv[0] by ./a.out,hello For the first time

Two inputs ,world For the third input ;

ok, Here we are , I think I have understood well drilling main Function parameter usage ; If you think it's useful, you can like it , Comment in support of . thank ！！！