quick question

This is a discussion on quick question within the C++ Programming forums, part of the General Programming Boards category; Is there any functions in the stdlib to convert strings to lower or uppercase ?? I know there is tolower() ...

  1. #1
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    Cool quick question

    Is there any functions in the stdlib to convert strings to lower or uppercase ??


    I know there is tolower() and toupper() for char.


    Is it best to just use a char array instead of strings and work through the array in a for loop ??

    Does everyone out there use String or char[index] ??

    Thanks

  2. #2
    zen
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    AFAIK you'll have to loop through the strings. It's pretty much the same process for character arrays or C++ strings -

    Code:
    #include <iostream> 
    #include <algorithm>
    #include <string> 
    #include <cstdlib>
    using namespace std;
    
    void mytoupper(char& c)
    {
    	c-=32;
    }
    int main() 
    { 
    
    	string name1 = "zen";
    	char name2 []= "zen";
    
    	//c string
    	for_each(&name2[0],&name2[strlen(name2)],mytoupper);
    
    	//c++ string
    	for_each(name1.begin(),name1.end(),mytoupper);
    
    	cout << name1 << endl << name2;
    
    	return 0; 
    }
    You could use normal for loops and the standard library toupper (I was bored).
    zen

  3. #3
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    that wont work if you pass in "ZEN" or "Zen" or anything with an uppercase char in it... you need to this:

    void MyToUpper(char& c)
    {
    c &= ~0x20;
    }

    void MyToLower(char& c)
    {
    c |= 0x20;
    }

    This will make sure that it works no matter what case is passed in

    U.
    Quidquid latine dictum sit, altum sonatur.
    Whatever is said in Latin sounds profound.

  4. #4
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    OK I know Uraldor' code works a treat, but I don't understand how it works ?

    Can anyone explain how the code works ?

    Ta

  5. #5
    zen
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    In ASCII the difference between the higher and lower case characters is that the lower case characters have the fifth bit set and the higher case don't. 0x20 (32 = 2^5) is the fifth bit, so Uraldors function removes that bit in toupper and sets it in tolower, using 0x20 and ~0x20 (0xDF) as masks.
    zen

  6. #6
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    Some compilers have strupr and strlwr in <string.h> or <cstring>. It may not be part of the standard though.

    char str[31];
    cout << "Enter a string:";
    cin >> str;
    strupr(str);
    cout << "str:" << str << endl;
    Last edited by swoopy; 12-19-2001 at 01:30 PM.

  7. #7
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    void AllUpperString(char* input)
    {
    for(i = 0; i < strlen(input); i++)
    {
    input[i] = toupper(input[i]);
    }
    }

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