correcting my last thread...

[demonus]

hi! I want it to let it sound a little more easier to understand!
I recognized that my last question, 'My C-Compiler doesn't like else if' was a little bit... .Let's no longer talk about it ;-)!

the code was something like this:

...
int main(int argc, char *argv[])
{
if (argc < 2 )
//usage menue!

else if (argv[1] = "Usageone")
//usage one

else if (argv[1] = "usagetwo")
//usage two

and so on...


When I compiled it, there was no errors or warnings!
When I startet it without arguments, the usage menue was shown like I thought it would happen, but then I was really ... scared about the next move: Checking the other arguments!
if I tried "programm usageone", everything was Ok, if I tried "programm usagetwo" or "programm usagenothing", the programm showed me usageONE! Ok? THIS was realy not the thing I expected! I tried different things, but nothing worked!
Can somebody help me now? Or is the answer the same like my last thread 'My C-Compiler doesn't like else if'? Answer please to [email protected] or this board!

P.S.: This page is the best!

[Magos]

1) When you compare, use == not =

2) You can't compare strings using ==, use strcmp();

int main(int ArgCount, char *Args[])
{
   if(ArgCount > 1)
   {
      if(strcmp(Args[1], "usageone") == 0)
      {
         //Yada yada...
      }
   }
}

Be careful. strcmp is case sensitive, meaning "Hello" != "hello".

[Shiro]

The reason why Usageone is always run is because of the condition, which is an assignment. You are trying to assign the string Usageone to argv[1]. An assignment evaluates to True, this condition is alwaysTrue.

For string comparing, you need the function strcmp(), which returns 0 when two strings are equal. You'll need string.h.

#include <string.h>

if (strcmp (string1, string2) == 0)
{
    /* string1 equals string 2 */
}

[Magos]

Originally posted by Shiro
An assignment evaluates to True, this condition is alwaysTrue.

An assignment returns the value that is being assigned, not true or false (but since true = !false = !0, that is true in almost every case ). That's why you can nest assignments:

X = Y = Z = 5;
X = Y = (Z = 5);
X = Y = 5;
X = (Y = 5);
X = 5;
(X = 5);
5;