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Is there some way to use variables in a system() command?
i've tried
but i only get an errormessage in the stdlib.h header (line 356), too many arguments in 'int system (const char*)'Code:system("%s",firstprogrampath);
as well in the actual program
(line 107) at this point in file.
So, is there any way to use variables in system();?
edit: also, firstprogrampath[50]; is a char variable. (string variable, i think the real name is?)
Yes, it is possible to do so. Just pay attention to what the man pages say about the inputs that you can pass to the system command. For example, this code will display the contents of the file "test.c"
But, keep in mind that system() does make your code less portableCode:# include<stdio.h>
# include<stdlib.h>
int main()
{
int num;
const char abc[]="cat test.c";
system(abc);
return 0;
}
If you must use system...
Use sprintf to create the command string.
Code:char buffer[100];
char *firstprogrampath = "foo.exe";
int value = 10;
...
/* buffer will contain "foo.exe 10" */
sprintf(buffer,"%s %d",firstprogrampath, value);
/* Now call system */
system(buffer);
I think he means something along the lines of:
edit: dang too late :@Code:#include <stdio.h>
#include <stdlib.h>
int main(void)
{
char command[BUFSIZ];
char firstProgramPath[] = "test";
sprintf(command, "%s", firstprogrampath);
system(command);
return 0;
}
Seeing as i got a few "If you have to use system..." then is there any other ways to execute a program from a variable?
The program is supposed to have a menu, with the options to add a program to the list, run a program from the list, remove a program from the list and save the list to the harddrive, all functions are yet to be implemented.
EDIT, also, here is the code (i am quite the newcomer so it is quite bulky, but it does what it should do atm).
Any tips or tricks on what could be improved are welcome.
Code:/* A program written by Afro for users to add
and start various applications from a list */
/*
TODO list
-Switch-case main menu and sub menu if possible
-"Run the program" function
-"delete latest program" function
-"exit" function -- DONE
-"save data" function
-Replace long IF-firstprogramexist with a function if possible
-Improve layout and add screen clearing
*/
/*------------------------------------------------------------------*/
/*----------------------- Headers ----------------------------------*/
/*------------------------------------------------------------------*/
#include <stdio.h>
#include <stdlib.h>
/*------------------------------------------------------------------*/
/* ---------------------- Functions --------------------------------*/
/*------------------------------------------------------------------*/
/*------------------------------------------------------------------*/
/* -------------------- Menu Variables -----------------------------*/
/*------------------------------------------------------------------*/
int firstChoice;
int secondChoice;
int programnumber;
/*------------------------------------------------------------------*/
/*------------------- Program variables ----------------------------*/
/*------------------------------------------------------------------*/
/* First program */
char firstprogramname[30];
char firstprogrampath[50];
int firstprogramexist;
/* Second program */
char secondprogramname[30];
char secondprogrampath[50];
int secondprogramexist;
/*Third Program */
char thirdprogramname[30];
char thirdprogrampath[50];
int thirdprogramexist;
/*Fourth Program */
char fourthprogramname[30];
char fourthprogrampath[50];
int fourthprogramexist;
/*Fifth Program */
char fifthprogramname[30];
char fifthprogrampath[50];
int fifthprogramexist;
/*------------------------------------------------------------------*/
/* ---------------- End of the beginning ---------------------------*/
/*------------------------------------------------------------------*/
int main()
{
programnumber=1;
/* Print info about the program */
printf("This is a program-starter written by Afro\n");
printf("It has a maximum capacity of five stored programs\n");
/*------------------------------------------------------------------*/
/*----------------------- MAIN MENU --------------------------------*/
/*------------------------------------------------------------------*/
for(;;)
{
printf("\nWhat do you want to do?\n\n");
printf("Run a program (Enter 1)\n");
printf("Show the programs in the list (Enter 2)\n");
printf("Add a program to the list (enter 3)\n");
printf("Delete the latest added program (enter 4)\n");
printf("Exit (enter 5)\n\n");
firstChoice=getchar();
fflush(stdin);
/*------------------------------------------------------------------*/
/*---------------------- Execute the programs ----------------------*/
/*------------------------------------------------------------------*/
if (firstChoice==49)
{
printf("Enter the corresponding number \n");
printf("of the program you want to run.\n");
fflush(stdin);
secondChoice=getchar();
if(secondChoice==49)
{
printf("Running %s",firstprogramname);
//system("%s",firstprogrampath);
}
else if(secondChoice==50)
{
printf("Running %s",secondprogramname);
//system("");
}
else if(secondChoice==51)
{
printf("Running %s",thirdprogramname);
//system("");
}
else if(secondChoice==52)
{
printf("Running %s",fourthprogramname);
//system("");
}
else if(secondChoice==53)
{
printf("Running %s",fifthprogramname);
//system("");
}
else
{
printf("Please enter a correct number between 1-5.");
}
} //end of the run the program "if"
/*------------------------------------------------------------------*/
/*---------------------- List the programs -------------------------*/
/*------------------------------------------------------------------*/
if (firstChoice==50)
{
printf("You wish to run a program\n");
printf("These are the programs that the computer has stored:\n");
if(firstprogramexist==1)
{
printf("Number 1:\t %s \n",firstprogramname);
}
if(secondprogramexist==1)
{
printf("Number 2:\t %s \n",secondprogramname);
}
if(thirdprogramexist==1)
{
printf("Number 3:\t %s \n",thirdprogramname);
}
if(fourthprogramexist==1)
{
printf("Number 4:\t %s \n",fourthprogramname);
}
if(fifthprogramexist==1)
{
printf("Number 5:\t %s \n",fifthprogramname);
}
else printf("There are no programs in the list.\n");
} //end of the list the programs "IF"
/*------------------------------------------------------------------*/
/*------------- The adding of the five possible programs -----------*/
/*------------------------------------------------------------------*/
else if (firstChoice==51 && programnumber==1)
{
printf("You wish to add a program\n");
printf("Please enter the name of the program:\n\n");
gets(firstprogramname);
printf("\n\nPlease enter the path to the program:\n");
fflush(stdin);
gets(firstprogrampath);
printf("The program will be shown as:\n %s\n\n",firstprogramname);
printf("The path to the program is:\n %s\n\n",firstprogrampath);
programnumber++;
firstprogramexist=1;
}
else if (firstChoice==51 && programnumber==2)
{
printf("You wish to add a program\n");
printf("Please enter the name of the program:\n\n");
gets(secondprogramname);
printf("\n\nPlease enter the path to the program:\n");
fflush(stdin);
gets(secondprogrampath);
printf("The program will be shown as:\n %s\n\n",secondprogramname);
printf("The path to the program is:\n %s\n\n",secondprogrampath);
programnumber++;
secondprogramexist=1;
}
else if (firstChoice==51 && programnumber==3)
{
printf("You wish to add a program\n");
printf("Please enter the name of the program:\n\n");
gets(thirdprogramname);
printf("\n\nPlease enter the path to the program:\n");
fflush(stdin);
gets(thirdprogrampath);
printf("The program will be shown as:\n %s\n\n",thirdprogramname);
printf("The path to the program is:\n %s\n\n",thirdprogrampath);
programnumber++;
thirdprogramexist=1;
}
else if (firstChoice==51 && programnumber==4)
{
printf("You wish to add a program\n");
printf("Please enter the name of the program:\n\n");
gets(fourthprogramname);
printf("\n\nPlease enter the path to the program:\n");
fflush(stdin);
gets(fourthprogrampath);
printf("The program will be shown as:\n %s\n\n",fourthprogramname);
printf("The path to the program is:\n %s\n\n",fourthprogrampath);
programnumber++;
fourthprogramexist=1;
}
else if (firstChoice==51 && programnumber==5)
{
printf("You wish to add a program\n");
printf("Please enter the name of the program:\n\n");
gets(fifthprogramname);
printf("\n\nPlease enter the path to the program:\n");
fflush(stdin);
gets(fifthprogrampath);
printf("The program will be shown as:\n %s\n\n",fifthprogramname);
printf("The path to the program is:\n %s\n\n",fifthprogrampath);
programnumber++;
fifthprogramexist=1;
}
/* Program-adding error (too many programs)*/
else if (firstChoice==51 && programnumber>5)
{
printf("You have reached the maximum amount of programs");
}
/*------------------------------------------------------------------*/
/*----------------- END OF PROGRAM ADDING --------------------------*/
/*------------------------------------------------------------------*/
/*------------------------------------------------------------------*/
/*----------------- DELETE LATEST ADDED PROGRAM --------------------*/
/*------------------------------------------------------------------*/
/*------------------------------------------------------------------*/
/*--------------------------- EXIT ---------------------------------*/
/*------------------------------------------------------------------*/
else if (firstChoice==53)
{
break;
}
/*False Character error */
else
{
printf("Enter a correct number.\n");
}
} // End of Loop
return(0);
} // End of program
Running a program from within another program is one of the topics in the FAQ.
Thanks guys, i got that part to work now.
- Don't use fflush(stdin). http://faq.cprogramming.com/cgi-bin/...&id=1043284351
- Don't use gets(). http://faq.cprogramming.com/cgi-bin/...&id=1043284351
- Using character literals like '1' is much more readable than numbers like 49.
- Rather than have firstprogram[], secondprogram[], etc, why not use a multidimensional array?
Then you can get rid of all of that duplicate code.Code:char programname[5][30];
Since you are designing a menu system, I see no reason why system() is not appropriate. Go ahead and use it. The other answers about using sprintf() to create the command string are the right info.Quote:
Originally Posted by Afro