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Having trouble passing bool type to function....need help

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Join Date: Sep 2005

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Toshkin78

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Having trouble passing bool type to function....need help

Sep 16th, 2005

Im having trouble sending a bool type to a function which returns a char string to a string.

I have provided the code below

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
/*
  Name: bool2.cpp   
  Copyright: 
  Author: Toshkin   
  Date: 06/09/05 21:56
  Description: passing string to boolean function returning boolean to 
*/
 
#include <iostream>
#include <cstring>
using namespace std;
 
 
 
bool inout(char *string); // function prototype
char outin(char *string,bool *bl);     //
int main()
{
    char str1[5];
    bool b;
    cout <<"Please enter the word \"in\" or \"out\": ";
    cin >>str1;
    /*if (strcmp (str1,"in") == 0) {        // redundant code....
             b = true;
             }
    else {
         b = false;
         }
    */
    b = inout(str1);
    cout << boolalpha << b << endl;
    cout <<"str1: "<<str1<<endl;
    outin(str1,b);
    cout <<"str1: "<<str1<<endl;
    system("PAUSE");
    return 0;
}
 
bool inout(char *string)                             // this works
{
 
     if (strcmp(string,"in") == 0){
        return true;
        }
     else if (strcmp(string,"out") == 0){
        return false;
          }
 
} // end inout
 
char outin(char *string,bool *bl)                    //  this doesn't work
{
 
     if (bl==1){
            string = "in";
            }
     else if (bl==0) {
          string = "out";
          }
     return string;
}
/*
  Name: bool2.cpp   
  Copyright: 
  Author: Toshkin   
  Date: 06/09/05 21:56
  Description: passing string to boolean function returning boolean to 
*/

#include <iostream>
#include <cstring>
using namespace std;



bool inout(char *string); // function prototype
char outin(char *string,bool *bl);     //
int main()
{
    char str1[5];
    bool b;
    cout <<"Please enter the word \"in\" or \"out\": ";
    cin >>str1;
    /*if (strcmp (str1,"in") == 0) {        // redundant code....
             b = true;
             }
    else {
         b = false;
         }
    */
    b = inout(str1);
    cout << boolalpha << b << endl;
    cout <<"str1: "<<str1<<endl;
    outin(str1,b);
    cout <<"str1: "<<str1<<endl;
    system("PAUSE");
    return 0;
}

bool inout(char *string)                             // this works
{
     
     if (strcmp(string,"in") == 0){
        return true;
        }
     else if (strcmp(string,"out") == 0){
        return false;
          }
     
} // end inout

char outin(char *string,bool *bl)                    //  this doesn't work
{
    
     if (bl==1){
            string = "in";
            }
     else if (bl==0) {
          string = "out";
          }
     return string;
}

Im using Bloodshed DevC++ 4.9.9.2
Your help will be greatly appreciated.
Cheers Toshkin!!!

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Join Date: Apr 2004

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Dave Sinkula Dave Sinkula is offline

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long time no c

Re: Having trouble passing bool type to function....need help

Sep 16th, 2005

You can't return arrays in C or C++. Nor can you copy arrays using assignment [edit]use strcpy to copy strings[/edit]. Is there some reason you aren't using std::string?

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Join Date: Jun 2005

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drock9975

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Re: Having trouble passing bool type to function....need help

Sep 17th, 2005

•

Originally Posted by Toshkin78

Im having trouble sending a bool type to a function which returns a char string to a string.

I have provided the code below
Help with Code Tags

C++ Syntax (Toggle Plain Text)
 
char outin(char *string,bool *bl)                    //  this doesn't work
{
 
     if (bl==1){
            string = "in";
            }
     else if (bl==0) {
          string = "out";
          }
     return string;
}
char outin(char *string,bool *bl) // this doesn't work { if (bl==1){ string = "in"; } else if (bl==0) { string = "out"; } return string; }
Im using Bloodshed DevC++ 4.9.9.2
Your help will be greatly appreciated.
Cheers Toshkin!!!

since you are passing the string in by pointer and not by value, you can directly alter the string in the function... however you can not simply do string = whatever... you need to do a strcpy(string, whatever) or if you want, use stricpy(string, whatever, length) and then remember to put the null terminator at the end... then your function doesn't need to return anything... both strcpy and stricpy are in <cstring> and you'll need to #include that

also when comparing a bool to a value you can simply write true or false instead of 0 and 1... works better for clarity purposes... makes it easier to read

hope this helps

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long time no c

Re: Having trouble passing bool type to function....need help

Sep 18th, 2005

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Originally Posted by drock9975

both strcpy and stricpy are in <cstring>

Not necessarily -- stricpy is not standard.

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Re: Having trouble passing bool type to function....need help

Sep 18th, 2005

This will work -- the function must return char* which is a pointer just like the parameter. But there is no point passing the parameter if the function is going to change and return the pointer.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
char* outin(char *string,bool *bl)
{
 
     if (bl==1){
            string = "in";
            }
     else if (bl==0) {
          string = "out";
          }
     return string;
}
char* outin(char *string,bool *bl)
{
    
     if (bl==1){
            string = "in";
            }
     else if (bl==0) {
          string = "out";
          }
     return string;
}

This would be more logical. And why are you passing the bool by reference instead of by value? The function isn't changing the value so you might as well pass by value.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
char* outin(bool bl)
{
    char* string = 0;
     if (bl==1){
            string = "in";
            }
     else if (bl==0) {
          string = "out";
          }
     return string;
}
char* outin(bool bl)
{
    char* string = 0;
     if (bl==1){
            string = "in";
            }
     else if (bl==0) {
          string = "out";
          }
     return string;
}