tolstoyleo
asked on
Basic Questions I Think
I am writing a command line program and I need to be able to accept 2 arguments, and I'm just trying to pass them on as strings or arrays to another function.... here goes some code...
#include <stdio.h>
#include <winsock.h>
void doSocketStuff(char[]);
int main(int argc, char *argv[])
{
if (argc != 2) {
int a = errorMessage(1);
} else {
doSocketStuff(argv); // <------- error msg is here
}
return 0;
}
int errorMessage(int em)
{
if (em == 1) {
printf("Usage - Source IPADDRESS,PORT\n\n");
}
system("PAUSE");
return 1;
}
void doSocketStuff(char strIP[])
{
printf("IP ADDRESS = %s\n",strIP[0]);
printf("Port = %s\n",strIP[1]);
}
when I make the function call to "doSocketStuff" I get a couple of errors:
like: passing arg 1 of 'dosocketstuff' from incompatible pointer type
I don't understand how i'm supposed to pass it as a string from the argument array basically...
thanks all
-Matt
#include <stdio.h>
#include <winsock.h>
void doSocketStuff(char[]);
int main(int argc, char *argv[])
{
if (argc != 2) {
int a = errorMessage(1);
} else {
doSocketStuff(argv); // <------- error msg is here
}
return 0;
}
int errorMessage(int em)
{
if (em == 1) {
printf("Usage - Source IPADDRESS,PORT\n\n");
}
system("PAUSE");
return 1;
}
void doSocketStuff(char strIP[])
{
printf("IP ADDRESS = %s\n",strIP[0]);
printf("Port = %s\n",strIP[1]);
}
when I make the function call to "doSocketStuff" I get a couple of errors:
like: passing arg 1 of 'dosocketstuff' from incompatible pointer type
I don't understand how i'm supposed to pass it as a string from the argument array basically...
thanks all
-Matt
>I don't understand how i'm supposed to pass it as a string from the argument array basically
If you wanted to pass a single string instead of an array of strings, then modify your function call
>doSocketStuff(argv);
to pass a single string such as argv[1] etc to the function .... here you are passing an array of char *s (each char * holds a string ... so effectively it is an array of strings and not a single string)
If you wanted to pass a single string instead of an array of strings, then modify your function call
>doSocketStuff(argv);
to pass a single string such as argv[1] etc to the function .... here you are passing an array of char *s (each char * holds a string ... so effectively it is an array of strings and not a single string)
ASKER
I changed the function but i'm getting the same error...
tolstoyleo,
Post your modified code so that we could help more ....Also let us know the error message u get on compiling the code
Amit
Post your modified code so that we could help more ....Also let us know the error message u get on compiling the code
Amit
ASKER
ok... i'm kind of lost getting back into C... so thanks for bearing in there...
what is wrong with doing this:
#include <stdio.h>
void repeater(char[]);
int main(int argc, char *argv[]) {
repeater(argv);
return 0;
}
void repeater(char *arrVar[]) {
printf("%s\n",arrVar[0]);
}
I get an undefined reference to "repeater" error.. but besides that... when I try playing with just passing the arguments to another function from the command .. it's just not working out for me... i keep getting pointer type errors...
what is wrong with doing this:
#include <stdio.h>
void repeater(char[]);
int main(int argc, char *argv[]) {
repeater(argv);
return 0;
}
void repeater(char *arrVar[]) {
printf("%s\n",arrVar[0]);
}
I get an undefined reference to "repeater" error.. but besides that... when I try playing with just passing the arguments to another function from the command .. it's just not working out for me... i keep getting pointer type errors...
ASKER
This is the modified code from the first posting of code...
#include <stdio.h>
#include <winsock.h>
//void doSocketStuff(char);
int main(int argc, char *argv[])
{
if (argc != 2) {
int a = errorMessage(1);
} else {
doSocketStuff(argv);
}
return 0;
}
int errorMessage(int em)
{
if (em == 1) {
printf("Usage - Source IPADDRESS,PORT\n\n");
}
system("PAUSE");
return 1;
}
void doSocketStuff(char *strIP[])
{
printf("IP ADDRESS = %s\n",strIP[0]);
printf("Port = %s\n",strIP[1]);
}
here are the errors:
26 C:\cpp\programs\source\soc
[Warning] type mismatch with previous implicit declaration
11 C:\cpp\programs\source\soc
[Warning] previous implicit declaration of `doSocketStuff'
26 C:\cpp\programs\source\soc
[Warning] `doSocketStuff' was previously implicitly declared to return `int'
#include <stdio.h>
#include <winsock.h>
//void doSocketStuff(char);
int main(int argc, char *argv[])
{
if (argc != 2) {
int a = errorMessage(1);
} else {
doSocketStuff(argv);
}
return 0;
}
int errorMessage(int em)
{
if (em == 1) {
printf("Usage - Source IPADDRESS,PORT\n\n");
}
system("PAUSE");
return 1;
}
void doSocketStuff(char *strIP[])
{
printf("IP ADDRESS = %s\n",strIP[0]);
printf("Port = %s\n",strIP[1]);
}
here are the errors:
26 C:\cpp\programs\source\soc
[Warning] type mismatch with previous implicit declaration
11 C:\cpp\programs\source\soc
[Warning] previous implicit declaration of `doSocketStuff'
26 C:\cpp\programs\source\soc
[Warning] `doSocketStuff' was previously implicitly declared to return `int'
ASKER CERTIFIED SOLUTION
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#include <stdio.h>
void repeater(char[]);
int main(int argc, char *argv[]) {
repeater(argv);
return 0;
}
void repeater(char *arrVar[]) {
printf("%s\n",arrVar[0]);
}
Initially, the function prototype for 'repeater' tells the compiler that u have a function called 'repeater' which takes a char array (pointer) as a parameter and returns void
When in main, u call, repeater ( argv ), u are passing an array of char pointers [can say an array of strings] to the function repeater BUT the function prototype u declared earlier expects just a char string & not an array of char strings
Thus, u get an undefied reference
Amit
void repeater(char[]);
int main(int argc, char *argv[]) {
repeater(argv);
return 0;
}
void repeater(char *arrVar[]) {
printf("%s\n",arrVar[0]);
}
Initially, the function prototype for 'repeater' tells the compiler that u have a function called 'repeater' which takes a char array (pointer) as a parameter and returns void
When in main, u call, repeater ( argv ), u are passing an array of char pointers [can say an array of strings] to the function repeater BUT the function prototype u declared earlier expects just a char string & not an array of char strings
Thus, u get an undefied reference
Amit
problem is that by default C expects a function to return an int while your function is returning void ... thus the mismatch
ASKER
I'm going to accept the last 2 of sunny coders and award the pointers... one more question but you don't have to answer if you don't want to:
why is the first value in the argv array = the location of the program like:
argv[0] = "C:\cpp\programs\source\so
and the second one:
argv[1] = whatever the arguments i typed: 3.3.3.3 , 80
why is the first value in the argv array = the location of the program like:
argv[0] = "C:\cpp\programs\source\so
and the second one:
argv[1] = whatever the arguments i typed: 3.3.3.3 , 80
well that is the way C works ... argv[0] is always the name of the program which is invoked and the following paramteres are arguments to the program ...
Why is it so ? Well I can't recollect where but I saw a couple of programs which saved the name of their executables for restart or some other procesing
Why is it so ? Well I can't recollect where but I saw a couple of programs which saved the name of their executables for restart or some other procesing
>int main(int argc, char *argv[])
as you notice, argv is an array of char pointers
>void doSocketStuff(char strIP[])
this expects an array of chars ... and you are passing it an array of char *s ....
change the declaration to
void doSocketStuff(char * strIP[]) if you wish to pass it an array of char pointers
Sunnycoder