cstring.cpp

C/C++程序设计导论（第二版）》程序源文件

// CString.cpp   C++ String implementation file

#include <math.h>
#include <string.h>
#include <stdlib.h>

#include "CString.h"

String::String ()          							// simple constructor
 { 	cells[0] = NULLC;
 }

String::operator char* ()							// outward cast conversion
 {	return (cells);
 }

String::String (char arg[ ])							// literal constructor
 { 	strncpy (cells, arg, MAX-1);
 }

String String::operator= (String a)							// assignment of strings
 { 	strcpy (cells, a.cells);
   	return (*this);
 }

int String::Atoi ()							// converts text to int
 { 	return (atoi(cells));    					 		// just a wrapper for atoi(char*)
 }

float String::Atof ()							// converts text to float
 { 	return (atof(cells));							// just a wrapper for atof(char*)
 }

int String::Length ()							// returns length of string
 { 	return (strlen(cells));							// just a wrapper for strlen(char*)
 }

void String::InputStr (istream& in)							// input function
 { 	in >> cells;
 }

void String::OutputStr (ostream& out)							// output function
 { 	out << cells;
 }

int String::operator== (String a)							// test for equality
 { 	return (!strcmp (cells, a.cells));
 }

int String::operator!= (String a)    							// test for inequality
 { 	return (strcmp (cells, a.cells));
 }

int String::operator< (String a)							// test for less than
 { 	if (strcmp (cells, a.cells) < 0)
		return (1);
	else return (0);
 }

int String::operator> (String a)	   						// test for greater than
 { 	if (strcmp (cells, a.cells) > 0)
		return (1);
	else return (0);
 }

int String::operator<= (String a)							// test for LEQ
 {	 if (strcmp (cells, a.cells) <= 0)
		return (1);
	else return (0);
 }

int String::operator>= (String a)							// test for GEQ
 { 	if (strcmp (cells, a.cells) >= 0)
		return (1);
	else return (0);
 }

String String::Substr (int n, int size)							// substring copy
 {	String temp;
	if (n < MAX-1)
	 {	strncpy (temp.cells, cells+n, size);
		temp.cells[size] = NULLC;
	 }
	return (temp);
 }

int String::Contains (String a)							// test for substring
 {	char *ptr;
	ptr = strstr (cells, a.cells);
	if (ptr == NULL) return (-1);
	else return ((int)ptr - (int)cells);
 }

String String::operator+ (String s)							// concatenation
{ 	int n;
  	String temp;
  	strcpy (temp.cells, cells);
  	n = strlen(cells);
  	if (MAX-n-1 > 0) 
		strncpy (temp.cells+n, s.cells, MAX-n-1);
  	return (temp);
}

char String::Onechar (int n)							// return a single character
{	if (n < strlen(cells))
		return (cells[n]);
	else return (-1);
}

void String::Onechar (int n, char c)							// replace a single character
{	if (n < strlen(cells))
		cells[n] = c;
}

istream& operator>> (istream& in, String& a)	   // prototype for overloaded >>
 { 	a.InputStr(in);                              							// simply calls the right
	return (in);						//   member function
 }

ostream& operator<< (ostream& out, String a)	   // prototype for overloaded <<
 { 	a.OutputStr(out);				                  			//   simply calls the right
	return (out);				                     		//   member function
 }