String Manipulation Made Easy with std::string Algorithms

String Manipulation Made Easy with std::string Algorithms

ext processors, spellcheckers, and IDEs are just a few classic examples of applications that need to manipulate strings extensively. Web-oriented applications also make heavy use of strings for generating text, processing clients’ requests, processing scripts, and logging. Clearly, string-savviness is becoming an important skill in many programming areas. In the following sections, learn how to implement some common string-oriented tasks using std::string and its member functions.

How can you perform case-insensitive comparisons and find and replace operations with string objects?

Use the specialized algorithms of class std::string.

Case Insensitive Comparisons
The overloaded == operator of std::string performs a case-sensitive lexicographical comparison. This feature is useful in implementing IDEs of case-sensitive programming languages such as C++. However, there are situations in which you need a case-insensitive comparison. Suppose you need to locate all of the occurrences of a certain word in a document:

string Evita_lyrics  ="Mourning all day and mourning all night";

A common technique for eliminating case differences is transforming the entire string to uppercase letters. However, this approach is ruled out if the original string must remain intact. Alternatively, you can let the comparison function locally convert each letter to its uppercase counterpart as shown in the following code listing:

int nocase_cmp(const string & s1, const string& s2) {  string::const_iterator it1=s1.begin();  string::const_iterator it2=s2.begin();  //stop when either string's end has been reached  while ( (it1!=s1.end()) && (it2!=s2.end()) )   {     if(::toupper(*it1) != ::toupper(*it2)) //letters differ?     // return -1 to indicate smaller than, 1 otherwise      return (::toupper(*it1)  < ::toupper(*it2)) ? -1 : 1;     //proceed to the next character in each string    ++it1;    ++it2;  }  size_t size1=s1.size(), size2=s2.size();// cache lengths   //return -1,0 or 1 according to strings' lengths    if (size1==size2)       return 0;    return (size1

Test this function:

string s1="Mourning";string s2="mourning";int n=nocase_cmp(s1, s2); //n=0

As expected, the result is 0 indicating that the strings are identical is spite of the case difference of their initial letter.

Author's Note: Don't be tempted to hide the nocase_cmp() function in an overloaded == as this will clash with the standard (and case-sensitive) == operator.

Searching a Substring Within a String
Searching a substring within a string is another common task in text-oriented apps. The Standard Library defines several specialized overloaded versions of string::find(). These overloaded versions take const string&, const char *, or char as a sought-after value. For the sake of brevity, I will focus only on locating a string object within another string object:

string phrase="Franco's rain in Spain";string sought = "rain";int pos=phrase.find(sought); // pos=9

find() returns the position of sought's first character within phrase. This position can then be used for further manipulations such as deleting the sought-after string or replacing it with another value. Test if the search succeeded like this:

if(pos!= string::npos) //successelse   //not found

If the sought-after string wasn't found, find() will return string::npos, which is an agreed-upon constant value indicating an invalid position in any string.

 
Figure 1: Replacing a Substring.

Replacing a Substring
To replace the sought-after value, use the replace() function which also has several overloaded versions. Again, use the canonical version which takes three arguments: the position to which the replacement string should be written, the length of the substring to be replaced, and an overriding string. For example, the following snippet corrects a typo in phrase by replacing 'rain' with 'reign':

phrase.replace(pos, sought.size(), replacement); cout<

Figure 1 shows what the output looks like.

In fact, the search and replace operations can be combined into a single statement:

phrase.replace(phrase.find(sought),                sought.size(),                replacement);

Remember that this form should be used only when you're certain that the sought-after value exists in the containing string (this may be the case if the processed sentence is machine-generated, for example). If there's no such guarantee, check whether the search operation succeeded before calling replace().

 
Figure 2: replace() automatically adjusts its object's capacity to fit to its new size.

Superb Strings
I silently ignored an issue that may have perturbed you: 'reign' is one character longer than the replaced value 'rain' and yet the program didn't extend the original string's size before calling replace(). Is this an oversight? No, it isn't. replace() automatically adjusts its object's capacity to fit to its new size. To convince the skeptics among you, I'll use a longer replacement string and check the string object's capacity before and after the replace() call:

cout<<"original string capacity: "<

As you can see, the resulting string and its capacity were expanded automatically:

And that, my friends, is the beauty of std::string!

devx-admin

devx-admin

Share the Post:
Software Development

Top Software Development Companies

Looking for the best in software development? Our list of Top Software Development Companies is your gateway to finding the right tech partner. Dive in

India Web Development

Top Web Development Companies in India

In the digital race, the right web development partner is your winning edge. Dive into our curated list of top web development companies in India,

USA Web Development

Top Web Development Companies in USA

Looking for the best web development companies in the USA? We’ve got you covered! Check out our top 10 picks to find the right partner

Clean Energy Adoption

Inside Michigan’s Clean Energy Revolution

Democratic state legislators in Michigan continue to discuss and debate clean energy legislation in the hopes of establishing a comprehensive clean energy strategy for the

Chips Act Revolution

European Chips Act: What is it?

In response to the intensifying worldwide technology competition, Europe has unveiled the long-awaited European Chips Act. This daring legislative proposal aims to fortify Europe’s semiconductor

Revolutionized Low-Code

You Should Use Low-Code Platforms for Apps

As the demand for rapid software development increases, low-code platforms have emerged as a popular choice among developers for their ability to build applications with

Software Development

Top Software Development Companies

Looking for the best in software development? Our list of Top Software Development Companies is your gateway to finding the right tech partner. Dive in and explore the leaders in

India Web Development

Top Web Development Companies in India

In the digital race, the right web development partner is your winning edge. Dive into our curated list of top web development companies in India, and kickstart your journey to

USA Web Development

Top Web Development Companies in USA

Looking for the best web development companies in the USA? We’ve got you covered! Check out our top 10 picks to find the right partner for your online project. Your

Clean Energy Adoption

Inside Michigan’s Clean Energy Revolution

Democratic state legislators in Michigan continue to discuss and debate clean energy legislation in the hopes of establishing a comprehensive clean energy strategy for the state. A Senate committee meeting

Chips Act Revolution

European Chips Act: What is it?

In response to the intensifying worldwide technology competition, Europe has unveiled the long-awaited European Chips Act. This daring legislative proposal aims to fortify Europe’s semiconductor supply chain and enhance its

Revolutionized Low-Code

You Should Use Low-Code Platforms for Apps

As the demand for rapid software development increases, low-code platforms have emerged as a popular choice among developers for their ability to build applications with minimal coding. These platforms not

Cybersecurity Strategy

Five Powerful Strategies to Bolster Your Cybersecurity

In today’s increasingly digital landscape, businesses of all sizes must prioritize cyber security measures to defend against potential dangers. Cyber security professionals suggest five simple technological strategies to help companies

Global Layoffs

Tech Layoffs Are Getting Worse Globally

Since the start of 2023, the global technology sector has experienced a significant rise in layoffs, with over 236,000 workers being let go by 1,019 tech firms, as per data

Huawei Electric Dazzle

Huawei Dazzles with Electric Vehicles and Wireless Earbuds

During a prominent unveiling event, Huawei, the Chinese telecommunications powerhouse, kept quiet about its enigmatic new 5G phone and alleged cutting-edge chip development. Instead, Huawei astounded the audience by presenting

Cybersecurity Banking Revolution

Digital Banking Needs Cybersecurity

The banking, financial, and insurance (BFSI) sectors are pioneers in digital transformation, using web applications and application programming interfaces (APIs) to provide seamless services to customers around the world. Rising

FinTech Leadership

Terry Clune’s Fintech Empire

Over the past 30 years, Terry Clune has built a remarkable business empire, with CluneTech at the helm. The CEO and Founder has successfully created eight fintech firms, attracting renowned

The Role Of AI Within A Web Design Agency?

In the digital age, the role of Artificial Intelligence (AI) in web design is rapidly evolving, transitioning from a futuristic concept to practical tools used in design, coding, content writing

Generative AI Revolution

Is Generative AI the Next Internet?

The increasing demand for Generative AI models has led to a surge in its adoption across diverse sectors, with healthcare, automotive, and financial services being among the top beneficiaries. These

Microsoft Laptop

The New Surface Laptop Studio 2 Is Nuts

The Surface Laptop Studio 2 is a dynamic and robust all-in-one laptop designed for creators and professionals alike. It features a 14.4″ touchscreen and a cutting-edge design that is over

5G Innovations

GPU-Accelerated 5G in Japan

NTT DOCOMO, a global telecommunications giant, is set to break new ground in the industry as it prepares to launch a GPU-accelerated 5G network in Japan. This innovative approach will

AI Ethics

AI Journalism: Balancing Integrity and Innovation

An op-ed, produced using Microsoft’s Bing Chat AI software, recently appeared in the St. Louis Post-Dispatch, discussing the potential concerns surrounding the employment of artificial intelligence (AI) in journalism. These

Savings Extravaganza

Big Deal Days Extravaganza

The highly awaited Big Deal Days event for October 2023 is nearly here, scheduled for the 10th and 11th. Similar to the previous year, this autumn sale has already created

Cisco Splunk Deal

Cisco Splunk Deal Sparks Tech Acquisition Frenzy

Cisco’s recent massive purchase of Splunk, an AI-powered cybersecurity firm, for $28 billion signals a potential boost in tech deals after a year of subdued mergers and acquisitions in the

Iran Drone Expansion

Iran’s Jet-Propelled Drone Reshapes Power Balance

Iran has recently unveiled a jet-propelled variant of its Shahed series drone, marking a significant advancement in the nation’s drone technology. The new drone is poised to reshape the regional

Solar Geoengineering

Did the Overshoot Commission Shoot Down Geoengineering?

The Overshoot Commission has recently released a comprehensive report that discusses the controversial topic of Solar Geoengineering, also known as Solar Radiation Modification (SRM). The Commission’s primary objective is to

Remote Learning

Revolutionizing Remote Learning for Success

School districts are preparing to reveal a substantial technological upgrade designed to significantly improve remote learning experiences for both educators and students amid the ongoing pandemic. This major investment, which

Revolutionary SABERS Transforming

SABERS Batteries Transforming Industries

Scientists John Connell and Yi Lin from NASA’s Solid-state Architecture Batteries for Enhanced Rechargeability and Safety (SABERS) project are working on experimental solid-state battery packs that could dramatically change the

Build a Website

How Much Does It Cost to Build a Website?

Are you wondering how much it costs to build a website? The approximated cost is based on several factors, including which add-ons and platforms you choose. For example, a self-hosted

Battery Investments

Battery Startups Attract Billion-Dollar Investments

In recent times, battery startups have experienced a significant boost in investments, with three businesses obtaining over $1 billion in funding within the last month. French company Verkor amassed $2.1

©2023 Copyright DevX - All Rights Reserved. Registration or use of this site constitutes acceptance of our Terms of Service and Privacy Policy.

Sitemap