Get data from a stream until EOF ignoring whitespace

getlnw.h

#include <cstdio>
#include <cstdlib>

/**
 * @brief getlnw Get data from a stream until EOF ignoring whitespace
 * @param input the given input stream
 * @return returns a pointer to the string.
 * @note you have to free() the string manually
 */
char* getlnw( FILE *input = stdin )
{
    char *str;
    unsigned int length = 0;
    str = (char*)malloc( sizeof(char) );
    str[0] = '\0';

    short chr;
    while( (chr = getc( input )) != EOF )
    {
        switch ( chr ) {
        case ' ':
        case '\t':
        case '\n':
            continue;
            break;
        }

        str[length] = (char)chr;
        length +=   2;
        str = (char*)realloc( str, length + 1 );
        --length;
        str[length] = '\0';
    }

    return str;
}

int main( int argc, char *argv[] )
{
    // A newline before the Ctrl+D may be required to force flushing the stdin buffer
    printf( "Enter string (Press Ctrl+D to terminate input)" );
    char *crypto = getlnw();
    printf( "string: %s\n", crypto );
    
    free( crypto );
    
    return 0;
}