Follow Techotopia on Twitter

On-line Guides
All Guides
eBook Store
iOS / Android
Linux for Beginners
Office Productivity
Linux Installation
Linux Security
Linux Utilities
Linux Virtualization
Linux Kernel
System/Network Admin
Scripting Languages
Development Tools
Web Development
GUI Toolkits/Desktop
Mail Systems
Eclipse Documentation

How To Guides
General System Admin
Linux Security
Linux Filesystems
Web Servers
Graphics & Desktop
PC Hardware
Problem Solutions
Privacy Policy




Thinking in C++ Vol 2 - Practical Programming
Prev Home Next

Finding in reverse

If you need to search through a string from end to beginning (to find the data in last in / first out order), you can use the string member function rfind( ):

//: C03:Rparse.h
#ifndef RPARSE_H
#define RPARSE_H
#include <cstddef>
#include <string>
#include <vector>
#include "../TestSuite/Test.h"
using std::size_t;
using std::string;
using std::vector;
class RparseTest : public TestSuite::Test {
// To store the words:
vector<string> strings;
void parseForData() {
// The ';' characters will be delimiters
string s("now.;sense;make;to;going;is;This");
// The last element of the string:
int last = s.size();
// The beginning of the current word:
size_t current = s.rfind(';');
// Walk backward through the string:
while(current != string::npos) {
// Push each word into the vector.
// Current is incremented before copying
// to avoid copying the delimiter:
strings.push_back(s.substr(current, last - current));
// Back over the delimiter we just found,
// and set last to the end of the next word:
current -= 2;
last = current + 1;
// Find the next delimiter:
current = s.rfind(';', current);
// Pick up the first word -- it's not
// preceded by a delimiter:
strings.push_back(s.substr(0, last));
void testData() {
// Test them in the new order:
test_(strings[0] == "This");
test_(strings[1] == "is");
test_(strings[2] == "going");
test_(strings[3] == "to");
test_(strings[4] == "make");
test_(strings[5] == "sense");
test_(strings[6] == "now.");
string sentence;
for(size_t i = 0; i < strings.size() - 1; i++)
sentence += strings[i] += " ";
// Manually put last word in to avoid an extra space:
sentence += strings[strings.size() - 1];
test_(sentence == "This is going to make sense now.");
void run() {
#endif // RPARSE_H ///:~
//: C03:Rparse.cpp
//{L} ../TestSuite/Test
#include "Rparse.h"
int main() {
RparseTest t;;
} ///:~

The string member function rfind( ) backs through the string looking for tokens and reports the array index of matching characters or string::npos if it is unsuccessful.

Thinking in C++ Vol 2 - Practical Programming
Prev Home Next

   Reproduced courtesy of Bruce Eckel, MindView, Inc. Design by Interspire