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Full Discussion: conversion to 'char' from 'int' warning
Top Forums Programming conversion to 'char' from 'int' warning Post 302478326 by achenle on Tuesday 7th of December 2010 04:24:43 PM
Old 12-07-2010
The declaration for tolower() is:

Code:
int tolower( int );

The function takes an int argument, and returns an int result. Since the cast from char to int is probably from 8 to 16 bits, no data is lost. But on the cast back to char from the int return, the change from 16 to 8 bits means data could be lost.

Of course, changing the contents of the string object passed to ToLower() isn't going to change the contents of the string in the calling code. Since the object is passed by value, the object that the ToLower() method operates on is a copy of the object in the calling code. For example, this code

Code:
#include <ctype.h>
#include <string>
#include <iostream>

using namespace std;

void toLowerVal( string str )
{
    for ( int ii = 0; ii < str.length(); ii++ )
    {
        str[ ii ] = ( char ) ::tolower( str[ ii ] );
    }
}

void toLowerRef( string &str )
{
    for ( int ii = 0; ii < str.length(); ii++ )
    {
        str[ ii ] = ( char ) ::tolower( str[ ii ] );
    }
}

int main( int argc, char **argv )
{
    for ( int ii = 1; ii < argc; ii++ )
    {
        string s1 = argv[ ii ];
        cout << s1 << endl;
        toLowerVal( s1 );
        cout << s1 << endl;
        toLowerRef( s1 );
        cout << s1 << endl;
    }

    return( 0 );
}

produces this output:

Code:
bash-3.2$ ./str ASDf as1FFFF
ASDf
ASDf
asdf
as1FFFF
as1FFFF
as1ffff

Note that calls to toLowerVal() do not change the data contained in the calling code.
 

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LEARN ABOUT SUSE

tiffwarning

TIFFWarning(3TIFF)														TIFFWarning(3TIFF)

NAME

       TIFFWarning, TIFFSetWarningHandler - library warning interface

SYNOPSIS

       #include <tiffio.h>

       void TIFFWarning(const char *module, const char *fmt, ...)

       #include <stdargh.h>

       typedef void (*TIFFWarningHandler)(const char *module, const char *fmt, va_list ap);

       TIFFWarningHandler TIFFSetWarningHandler(TIFFWarningHandler handler);

DESCRIPTION

       TIFFWarning  invokes the library-wide warning handler function to (normally) write a warning message to the stderr.  The fmt parameter is a
       printf(3S) format string, and any number arguments can be supplied. The module parameter is interpreted as  a  string  that,  if  non-zero,
       should be printed before the message; it typically is used to identify the software module in which a warning is detected.

       Applications that desire to capture control in the event of a warning should use TIFFSetWarningHandler to override the default warning han-
       dler.  A NULL(0) warning handler function may be installed to suppress error messages.

RETURN VALUES

       TIFFSetWarningHandler returns a reference to the previous error handling function.

SEE ALSO

       TIFFError(3TIFF), libtiff(3TIFF), printf(3)

       Libtiff library home page: http://www.remotesensing.org/libtiff/

libtiff 							 October 15, 1995						TIFFWarning(3TIFF)
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