Trying to compare to strings...

This is a discussion on Trying to compare to strings... within the C++ Programming forums, part of the General Programming Boards category; No matter what the strings are this program always reads them as different strings... Code: #include <iostream> #include <stdlib.h> #include ...

  1. #1
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    Trying to compare to strings...

    No matter what the strings are this program always reads them as different strings...

    Code:
    #include <iostream>
    #include <stdlib.h>
    #include <string.h>
    
    
    int main(int argc, char *argv[])
    {
    
      char string1[20], string2[20];
      
      cout<<"Input 2 strings. This program will tell you if the 2\n strings are excactly the same  ";
      
      cin.getline(string1, 20);
      cout<<'\n';
      cin.getline(string2, 20);
      
      cout<<"The 2 strings you entered were "<<string1<<" and "<<string2<<'\n';
     
     strcmp(string1, string2);
      
      
          if(string1 == string2)
           {
             cout<<"The two strings you entered are the same";
           }
      
          if(string1 != string2)
           {
            cout<<"The two strings you entered are not the same";
           }
        
      system("PAUSE");	
      return 0;
    }
    Can someone explain why this isnt working and what i need to do to get it to work? Thankyou.
    Last edited by imortal; 05-16-2003 at 10:40 AM.
    ~matt~

  2. #2
    Open to suggestions Brighteyes's Avatar
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    >strcmp(string1, string2);
    You have to save the return value of strcmp, otherwise the call is useless:
    Code:
    int cmp = strcmp(string1, string2);
    
    if(cmp == 0)
    {
        cout<<"The two strings you entered are the same";
    }
    else
    {
        cout<<"The two strings you entered are not the same";
    }
    Or you can simple use the call to strcmp in the if statement:
    Code:
    if (strcmp(string1, string2) == 0)
    {
    Note that strcmp returns one of three values: 0 if both strings are equal, > 0 if the first string has a higher collective value than the second, and < 0 if the first string has a lower collective value than the second.
    p.s. What the alphabet would look like without q and r.

  3. #3
    Registered User major_small's Avatar
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    Re: Trying to compare to strings...

    Code:
    ...
      cin.getline(string1, 20);
      cout<<'\n';
      cin.getline(string2, 20);
    ...
    here's a suggestion: use cin.get() and include the terminating character (usually '\n') for the string, so the string can be less than 20 characters. That way the person presses enter, the get() stops, and the next get() continues, and is reading on the next line....

    Code:
    ...
     cin.get(string1,20,'\n');
     cin.get(string2,20,'\n');
    ...
    I think that works... if it doesn't work properly, put a cin.ignore(1,'\n') in between the two cin.get().

  4. #4
    Open to suggestions Brighteyes's Avatar
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    >That way the person presses enter, the get() stops, and the next get() continues, and is reading on the next line....
    Both get and getline remove the newline character from the input stream. The only difference is that getline discards it and get places it in the target string, either way you still move to the next line.
    p.s. What the alphabet would look like without q and r.

  5. #5
    Registered User major_small's Avatar
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    Originally posted by Brighteyes
    either way you still move to the next line.
    I thought with getline() you could read past a return character and include it as part of the string...
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  6. #6
    Open to suggestions Brighteyes's Avatar
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    >I thought with getline() you could read past a return character and include it as part of the string...
    You can if you specify the delimiting character as something different:
    Code:
    cin.getline(string, 20, '|'); // Read up to a pipe character
    Now if the stream contains "abc\ndef|", getline will appear to read two lines, placing everything except the pipe character in string.
    p.s. What the alphabet would look like without q and r.

  7. #7
    Registered User major_small's Avatar
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    that's what I thought... I just use get() to stop at a return character because there's no possibility of it passing that return character... but now that I see that getline() destroys it, I'll probably use that a little more often...

    note: when using get() the terminating character is left in the input stream... http://www.cppreference.com/cppio_details.html#get
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  8. #8
    Open to suggestions Brighteyes's Avatar
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    > I just use get() to stop at a return character because there's no possibility of it passing that return character...
    You can change the delimiting character for get as well, just like with getline.
    p.s. What the alphabet would look like without q and r.

  9. #9
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    Originally posted by Brighteyes

    Note that strcmp returns one of three values: 0 if both strings are equal, > 0 if the first string has a higher collective value than the second, and < 0 if the first string has a lower collective value than the second.
    what do you mean by collective...
    ~matt~

  10. #10
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    Never mind, i got it

    Thanks guys.
    ~matt~

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