Using the bytestring class


Introduction

The bytestring class provides methods for manipulating byte strings.

In addition to some unique methods, analogs for the standard C "memory" functions are provided. However, unlike the standard C functions, the bytestring methods are NULL safe. Your application will not crash if a NULL is passed in, and instead, will give intuitive results.


Manipulating Byte Strings

The bytestring class provides methods for zeroing, initializing, duplicating, and copying byte strings.

#include <rudiments/bytestring.h>
#include <rudiments/stdio.h>

int main(int argc, const char **argv) {

        unsigned char   buffer[9];


        // zero the buffer
        bytestring::zero(buffer,sizeof(buffer));

        stdoutput.write("all zeros:\n  ");
        stdoutput.safePrint(buffer,sizeof(buffer));
        stdoutput.write("\n\n");


        // set the buffer to all ones
        bytestring::set(buffer,1,sizeof(buffer));

        stdoutput.write("all ones:\n  ");
        stdoutput.safePrint(buffer,sizeof(buffer));
        stdoutput.write("\n\n");


        // copy some data into the buffer
        unsigned char   data[]={0,1,2,3,4,5,6,7,8};
        bytestring::copy(buffer,data,sizeof(data));

        stdoutput.write("after copying 0-8:\n  ");
        stdoutput.safePrint(buffer,sizeof(buffer));
        stdoutput.write("\n\n");


        // copy some overlapping data from one part of the buffer to another
        bytestring::copyWithOverlap(buffer,buffer+3,sizeof(buffer)-3);

        stdoutput.write("after copying with overlap:\n  ");
        stdoutput.safePrint(buffer,sizeof(buffer));
        stdoutput.write("\n\n");


        // copy a string into the buffer
        unsigned char   str[]="hello";
        bytestring::copyUntil(buffer,str,'\0',sizeof(str));

        stdoutput.write("after copying \"hello\":\n  ");
        stdoutput.safePrint(buffer,sizeof(buffer));
        stdoutput.write("\n\n");


        // copy some data into the buffer, swapping bytes as they are copied
        bytestring::copySwapBytes(buffer,data,sizeof(data));

        stdoutput.write("after copying 0-8, swapping bytes:\n  ");
        stdoutput.safePrint(buffer,sizeof(buffer));
        stdoutput.write("\n\n");
}

Comparing Byte Strings

The bytestring class also provides a compare() method for comparing two byte strings.

#include <rudiments/bytestring.h>
#include <rudiments/stdio.h>

int main(int argc, const char **argv) {

        unsigned char   buffer1[8];
        unsigned char   buffer2[8];


        // zero the buffers
        bytestring::zero(buffer1,sizeof(buffer1));
        bytestring::zero(buffer2,sizeof(buffer2));

        stdoutput.write("both zeroed:\n");
        stdoutput.printf("  does buffer1=buffer2?  %s\n\n",
                (!bytestring::compare(buffer1,buffer2,sizeof(buffer1)))?
                                                                "yes":"no");

        // set buffer2 to all ones
        bytestring::set(buffer2,1,sizeof(buffer2));

        stdoutput.write("buffer2 is all ones:\n");
        stdoutput.printf("  does buffer1=buffer2?  %s\n\n",
                (!bytestring::compare(buffer1,buffer2,sizeof(buffer1)))?
                                                                "yes":"no");

        // set the first half of buffer2 to zeros
        // and only compare the first half
        bytestring::set(buffer2,0,sizeof(buffer2)/2);

        stdoutput.write("first half of buffer2 is all zeros:\n");
        stdoutput.printf("  does 1/2 buffer1 = 1/2 buffer2?  %s\n\n",
                (!bytestring::compare(buffer1,buffer2,sizeof(buffer1)/2))?
                                                                "yes":"no");
}

Finding Data in Byte Strings

The charstring class also provides methods for finding characters or other character strings within character strings.

The findFirst() and findLast() methods return the first/last instance of a character or byte string within a byte string, or NULL if no match is found.

#include <rudiments/bytestring.h>
#include <rudiments/stdio.h>

int main(int argc, const char **argv) {

        // initialize buffer
        unsigned char   buffer[]={0,2,0,2,0,2,0};

        stdoutput.write("buffer : ");
        stdoutput.safePrint(buffer,sizeof(buffer));
        stdoutput.write("\n\n");


        // find first and last 0
        unsigned char   *firstzero=(unsigned char *)
                        bytestring::findFirst(buffer,0,sizeof(buffer));
        unsigned char   *lastzero=(unsigned char *)
                        bytestring::findLast(buffer,0,sizeof(buffer));

        stdoutput.write("first 0 : ");
        stdoutput.safePrint(firstzero,sizeof(buffer)-(firstzero-buffer));
        stdoutput.write('\n');

        stdoutput.write(" last 0 : ");
        stdoutput.safePrint(lastzero,sizeof(buffer)-(lastzero-buffer));
        stdoutput.write("\n\n");


        // find first and last 0,2,0 patterns
        unsigned char   pattern[]={0,2,0};

        unsigned char   *firstzerotwozero=(unsigned char *)
                        bytestring::findFirst(buffer,sizeof(buffer),
                                                pattern,sizeof(pattern));
        unsigned char   *lastzerotwozero=(unsigned char *)
                        bytestring::findLast(buffer,sizeof(buffer),
                                                pattern,sizeof(pattern));

        stdoutput.write("first 0,2,0 : ");
        stdoutput.safePrint(firstzerotwozero,
                                sizeof(buffer)-(firstzerotwozero-buffer));
        stdoutput.write('\n');

        stdoutput.write(" last 0,2,0 : ");
        stdoutput.safePrint(lastzerotwozero,
                                sizeof(buffer)-(lastzerotwozero-buffer));
        stdoutput.write("\n\n");
}