asked on

error LNK2019

hi experts,

im trying to compile this: https://www.experts-exchange.com/questions/20079662/base-64-encoding-and-decoding.html

but it give me some problems:

Linking...
LIBCD.lib(crt0.obj) : error LNK2019: unresolved external symbol _main referenced in function _mainCRTStartup
Debug/64.exe : fatal error LNK1120: 1 unresolved externals

Im not sure if im doing something wrong when i create the project or if this is a problem in visual studio.Net 2003?
Can any1 help me out or send me the version compiled? i need it urgently

thanks a lot.

jkr

If you do have a 'main()' function, you probably set the wrong project type. If not, add one. If the project should be a GUI app (i.e. with a 'WinMain()'), go to your project settings, choose the 'Link' tab and locate '/subsystem:console' in the text field at the bottom of the dialog. Change that to '/subsystem:windows'

jkr

>>Can any1 help me out or send me the version compiled?

Sure, but what exactly from that link is what you need to have compiled?

xapsx

ASKER

what u whant, i need a working base64 decode & encode. thanks

novitiate

//code.cpp

int main()
{
return 0;
}

Project->Settings->Link(Tab)->Project Options(ListBox)
chnage /subsystem:windows to /subsystem:console

_novi_

xapsx

ASKER

i've gone to:

Configuration Propreties>Linker>System ->
SubSystem = Console (/SUBSYSTEM:CONSOLE)

what is wrong?

thanks!

jkr

Are you having a 'main()', then?

You should 'wrap' the relevant code into one, e.g.

#include <stdio.h>
äinclude <string.h>
#include <stdlib.h>

static char* _cpBase64Encoding =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

void Base64Encode( char* cpInput, char* cpOutput )
{
int nIdx[ 4 ]; // will contain the indices of coded letters in
// _cpBase64Encoding string; valid values [0..64]; the value
// of 64 has special meaning - the padding symbol

// process the data (3 bytes of input provide 4 bytes of output)
while ( '\0' != *cpInput )
{
nIdx[0] = ((*cpInput) & 0xFC)>>2;
nIdx[1] = ((*cpInput) & 0x03)<<4;
cpInput++;
if ( '\0' != *cpInput )
{
nIdx[1] |= ((*cpInput) & 0xF0)>>4;
nIdx[2] = ((*cpInput) & 0x0F)<<2;
cpInput++;
if ( '\0' != (*cpInput) )
{
nIdx[2] |= ((*cpInput) & 0xC0) >> 6;
nIdx[3] = (*cpInput) & 0x3F;
cpInput++;
}
else
nIdx[3] = 64;
}
else
{ // refer to padding symbol '='
nIdx[2] = 64;
nIdx[3] = 64;
}

*(cpOutput+0) = *(_cpBase64Encoding + nIdx[0]);
*(cpOutput+1) = *(_cpBase64Encoding + nIdx[1]);
*(cpOutput+2) = *(_cpBase64Encoding + nIdx[2]);
*(cpOutput+3) = *(_cpBase64Encoding + nIdx[3]);
cpOutput += 4;
}

// set this to terminate output string
*cpOutput = '\0';

return;
}

void Base64Decode( char* cpInput, char* cpOutput )
{
int nIdx[ 4 ]; // will contain the indices of coded letters in
// _cpBase64Encoding string; valid values [0..64]; the value
// of 64 has special meaning - the padding symbol

// process the data (3 bytes of input provide 4 bytes of output
while ( '\0' != *cpInput )
{
nIdx[ 0 ] = nIdx[ 1 ] = nIdx[ 2 ] = nIdx[ 3 ] = 64;
nIdx[0] = (strchr( _cpBase64Encoding, (*cpInput) ) - _cpBase64Encoding);
cpInput++;
if ( '\0' != *cpInput )
{
nIdx[1] = (strchr( _cpBase64Encoding, (*cpInput) ) - _cpBase64Encoding);
cpInput++;
if ( '\0' != (*cpInput) )
{
nIdx[2] = (strchr( _cpBase64Encoding, (*cpInput) ) - _cpBase64Encoding);
cpInput++;
if ( '\0' != (*cpInput) )
{
nIdx[3] = (strchr( _cpBase64Encoding, (*cpInput) ) - _cpBase64Encoding);
cpInput++;
}
}
}

if ( nIdx[3] == 64 ) nIdx[3] = 0;
if ( nIdx[2] == 64 ) nIdx[2] = 0;
if ( nIdx[1] == 64 ) nIdx[1] = 0;

*(cpOutput+0) = (char)((nIdx[0]<<2) | (nIdx[1]>>4));
*(cpOutput+1) = (char)((nIdx[1]<<4) | (nIdx[2]>>2));
*(cpOutput+2) = (char)((nIdx[2]<<6) | nIdx[3]);
cpOutput += 3;
}

// set this to terminate output string
*cpOutput = '\0';

return;
}

void main () {

char sNonCoded[ 256 ];
char sEncoded[ 256 ];

strcpy( sNonCoded, "This is non-coded text" );
Base64Encode( sNonCoded, sEncoded );
printf( "Encoded: %s", sEncoded );
Base64Decode( sEncoded, sNonCoded );
printf( "Decoded back: %s", sNonCoded );
}

ASKER CERTIFIED SOLUTION

jkr

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xapsx

ASKER

thanks!!, its working, thanks a lot for your help.

but how can i decode or encode a string?

jkr

>>but how can i decode or encode a string?

You need to change the 'main()' function to do that for you, e.g.

void main () {

char sNonCoded[ 256 ];
char sEncoded[ 256 ];

printf("Please enter a string (256 bytes max)\n");
scanf( "%s", sNonCoded);
Base64Encode( sNonCoded, sEncoded );
printf( "Encoded: %s\n", sEncoded );
Base64Decode( sEncoded, sNonCoded );
printf( "Decoded back: %s\n", sNonCoded );
}

xapsx

ASKER

ty, great help.