Computer Science Canada int argc, char *argv[] vc++ 2010 |
| Author: | ScaryRat [ Sat Aug 14, 2010 4:16 pm ] |
| Post subject: | int argc, char *argv[] vc++ 2010 |
What does this mean? when many programmers declare their main function, there are always "int argc, char *argv[]" in the parameters : int main (int argc, char *argv[]) { } Could anyone tell me what it means? Btw is it declaring an integer and a pointer to an character array? |
|
| Author: | chrisbrown [ Sat Aug 14, 2010 7:26 pm ] | ||
| Post subject: | Re: int argc, char *argv[] vc++ 2010 | ||
They are command-line arguments. argc is short for argument count, argv: argument values. char *argv[] is an array of strings, which are just character arrays with a '\0' at the end. If your compiled program is called app.exe, invoking
results in argc = 2, argv[0] = "abc" and argv[1] = "123". Notice that 123 is a string, not an int. |
|||
| Author: | DtY [ Sat Aug 14, 2010 8:45 pm ] | ||
| Post subject: | Re: int argc, char *argv[] vc++ 2010 | ||
chrisbrown @ Sat Aug 14, 2010 7:26 pm wrote: They are command-line arguments. argc is short for argument count, argv: argument values.
argc would equal three; the first argument (argv[0] is always the command that was run that started the application)
char *argv[] is an array of strings, which are just character arrays with a '\0' at the end. If your compiled program is called app.exe, invoking
results in argc = 2, argv[0] = "abc" and argv[1] = "123". Notice that 123 is a string, not an int. so, argc = 3 argv[0] = "app.exe" argv[1] = "abc" argv[2] = "123" |
|||
| Author: | chrisbrown [ Sun Aug 15, 2010 8:12 am ] |
| Post subject: | RE:int argc, char *argv[] vc++ 2010 |
My mistake, thanks for catching that. |
|
| Author: | ScaryRat [ Tue Aug 24, 2010 9:42 am ] |
| Post subject: | RE:int argc, char *argv[] vc++ 2010 |
Thanks! Sorry for this question but what specifically is an argument? |
|
| Author: | TheGuardian001 [ Tue Aug 24, 2010 12:17 pm ] | ||||
| Post subject: | Re: int argc, char *argv[] vc++ 2010 | ||||
Arguments are bits of data given to the program when it is launched. For example, if you open a .txt file (or if you launch it from the command line), the command given to Windows is:
In which case "notepad" is the command, and "myFileName.txt" is the argument. So in this case,
No arguments are generally necessary to simply launch a program, however they are used to provide extra bits of information to the program which generally act as instructions for the program, whether it is a file to open, or a specific thing to do once they open. |
|||||
| Author: | ScaryRat [ Mon Aug 30, 2010 9:20 am ] |
| Post subject: | RE:int argc, char *argv[] vc++ 2010 |
I thought that you cannot pass arrays (argv[]) into functions (int main)? |
|
| Author: | TerranceN [ Mon Aug 30, 2010 9:56 am ] |
| Post subject: | RE:int argc, char *argv[] vc++ 2010 |
Go <a href="http://www.cplusplus.com/doc/tutorial/arrays/">here</a> and scroll down to "Arrays as Parameters". |
|
| Author: | DtY [ Mon Aug 30, 2010 4:47 pm ] |
| Post subject: | Re: RE:int argc, char *argv[] vc++ 2010 |
ScaryRat @ Mon Aug 30, 2010 9:20 am wrote: I thought that you cannot pass arrays (argv[]) into functions (int main)? In a function definition argv[] is equivalent to *argv, it's just a convenient way to point out that that argument is an array (*argv[] is also the same as **argv). |
|