Category : Files from Magazines
Archive   : DFPP01.ZIP
Filename : STRINGS.CPP

// -------- strings.cpp

#include "strings.h"

// ------- put a string into a String
void String::putstr(char *s)
{
delete sptr;
length = strlen(s);
sptr = new char[length+1];
strcpy(sptr, s);
}

// --- convert from char *
String::String(char *s)
{
sptr = NULL;
putstr(s);
}

// ------- copy constructor
String::String(String& s)
{
sptr = NULL;
putstr(s.sptr);
}

// -------- construct with a size and fill character
String::String(int len, char fill)
{
length = len;
sptr = new char[length+1];
memset(sptr, fill, length);
*(sptr+len) = '\0';
}

// -------- assignment
String& String::operator=(String &s)
{
if (this != &s)
putstr(s.sptr);
return *this;
}

// ------- concatenation operator (str1 + str2)
String String::operator+(String &s)
{
int ln = 0;
if (sptr)
ln += strlen(sptr);
if (s.sptr)
ln += strlen(s.sptr);
String temp(ln);
if (sptr)
strcpy(temp.sptr, sptr);
if (s.sptr)
strcat(temp.sptr, s.sptr);
return temp;
}

// ------ substring: right len chars
String String::right(int len)
{
String tmp;
if (sptr && len) {
int sln = strlen(sptr);
if (len > sln)
len = sln;
if (len)
tmp = String(sptr + sln - len);
}
return tmp;
}

// ------ substring: left len chars
String String::left(int len)
{
String tmp(len);
if (sptr && len) {
int sln = strlen(sptr);
if (len > sln)
len = sln;
if (len)
strncpy(tmp.sptr, sptr, len);
}
return tmp;
}

// ------ substring: middle len chars starting from where
String String::mid(int len, int where)
{
String tmp(len);
if (len && sptr && where < (int) strlen(sptr))
strncpy(tmp.sptr,sptr+where,len);
return tmp;
}

// ---- find offset to first instance of specified char
int String::FindChar(unsigned char ch)
{
if (sptr) {
char *cp = strchr(sptr, ch);
if (cp)
return (int) (cp - sptr);
}
return -1;
}

// ------ change the buffer length of a string
void String::ChangeLength(unsigned int newlen)
{
if (length == 0)
*this = String(newlen);
else {
char *cp = new char[newlen+1];
memset(cp, '\0', newlen+1);
if (sptr != NULL) {
strncpy(cp, sptr, newlen);
delete sptr;
}
sptr = cp;
length = newlen;
}
}