Are you aware of how strings operate in C++? Consider this: What if the true essence of strings lies not in the entirety but rather in their components? The substr() function in C++ serves as a formidable instrument for revealing concealed structures, navigating intricate data, and unraveling complicated algorithmic puzzles. Nonetheless, are you utilizing these substrings effectively? In this article, you will explore the notion of substrings in C++, from its fundamental syntax to practical implementations.
In C++, a substring is recognized as a segment of a larger string. The substr() function is an attribute of the std::string class that enables you to retrieve substrings from a specified string, while also delineating the starting position and length of the substring. The substring constitutes a portion of the std::string class. This member function assists programmers with text manipulation and data extraction.
Syntax:
string substr(size_t pos = 0, size_t len = npos) const;
The substr() function delivers a substring from the original string. The pos parameter determines the initial index of the first character included in the substring, while the len parameter indicates the count of characters to be extracted from the original string. Size_t is an unsigned integral type.
Parameters of substr() in C++ String
The substr() function accepts two parameters:
pos: This parameter determines the starting index of the string and must be within the limits of the original string.
If pos == string.length(), substr() returns an empty string.
If pos > string.length, the substr() function raises an out-of-range exception.
len: This defines the length of the substring; the default value of len is string::npos, which signifies till the end of the string.
Example:
Cpp
Code Copied!
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editor84117.setValue(decodedContent); // Set the default text
editor84117.clearSelection();
editor84117.setOptions({
maxLines: Infinity
});
function decodeHTML84117(input) {
var doc = new DOMParser().parseFromString(input, “text/html”);
return doc.documentElement.textContent;
}
// Function to copy code to clipboard
function copyCodeToClipboard84117() {
const code = editor84117.getValue(); // Get code from the editor
navigator.clipboard.writeText(code).then(() => {
jQuery(“.maineditor84117 .copymessage”).show();
setTimeout(function() {
jQuery(“.maineditor84117 .copymessage”).hide();
}, 2000);
}).catch(err => {
console.error(“Error copying code: “, err);
});
}
function runCode84117() {
var code = editor84117.getSession().getValue();
jQuery(“#runBtn84117 i.run-code”).show();
jQuery(“.output-tab”).click();
jQuery.ajax({
url: “https://intellipaat.com/blog/wp-admin/admin-ajax.php”,
type: “post”,
data: {
language: “cpp”,
code: code,
cmd_line_args: “”,
variablenames: “”,
action: “compilerajax”
},
success: function(response) {
var myArray = response.split(“~”);
var data = myArray[1];
jQuery(“.output84117”).html(“
function closeoutput84117() {
jQuery(“.maineditor84117 .code-editor-output”).hide();
}
“““javascript
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document.getElementById(“copyBtn84117”).addEventListener(“click”, copyCodeToClipboard84117);
document.getElementById(“runBtn84117”).addEventListener(“click”, runCode84117);
document.getElementById(“closeoutputBtn84117”).addEventListener(“click”, closeoutput84117);
Result:
The aforementioned C++ program employs the substr() function to extract a specific segment of a substring. In this instance, the string “Hello, World!” serves as the base string, and text.substr(7, 5) is utilized to get the substring starting from index 7, covering a total of 5 characters. Consequently, the substring “World” is retrieved.
Complexity of Substring in C++
The time complexity associated with substring in C++ is O(len), where len signifies the count of characters that need to be copied.
How does substr() in C++ Function?
The substr() function is used to extract the substring from the original string. When you call substr(pos, len) from a specified index in the original string, it begins by copying the characters. The len argument indicates how many characters to acquire from a given string. The substr() function yields the substring derived from the original string, starting at the designated position and encompassing the specified number of characters.
Return Result of substr() in C++
In C++, the method substr() produces a new string that is the result of the extracted substring. Generally, the return values are stored in a separate string or may be directly utilized in expressions.
Illustration of substr() in C++
Now, let’s review some instances that incorporate the substr() function in C++:
1. Substring Following a Character
In C++, the “substring following a character” retrieves the segment of the string that appears after a particular character. By utilizing the find() method, you can effortlessly locate the character’s position and then apply substr() to obtain the substring just beyond it. This is crucial for tasks such as parsing email addresses, URLs, and more.
Example:
Cpp
Code Copied!
var isMobile = window.innerWidth “);
editor76567.setValue(decodedContent); // Set the default text
editor76567.clearSelection();
editor76567.setOptions({
maxLines: Infinity
});
function decodeHTML76567(input) {
var doc = new DOMParser().parseFromString(input, “text/html”);
return doc.documentElement.textContent;
}
// Function to copy code to clipboard
function copyCodeToClipboard76567() {
const code = editor76567.getValue(); // Get code from the editor
navigator.clipboard.writeText(code).then(() => {
// alert(“Code copied to clipboard!”);
data: {
language: “cpp”,
code: code,
cmd_line_args: “”,
variablenames: “”,
action:”compilerajax”
},
success: function(response) {
var myArray = response.split(“~”);
var data = myArray[1];
jQuery(“.output76567”).html(“
"+data+"");
jQuery(".maineditor76567 .code-editor-output").show();
jQuery("#runBtn76567 i.run-code").hide();
}
})
}
function closeoutput76567() {
var code = editor76567.getSession().getValue();
jQuery(".maineditor76567 .code-editor-output").hide();
}
// Bind event listeners to the buttons
document.getElementById("copyBtn76567").addEventListener("click", copyCodeToClipboard76567);
document.getElementById("runBtn76567").addEventListener("click", runCode76567);
document.getElementById("closeoutputBtn76567").addEventListener("click", closeoutput76567);
Result:
The preceding C++ program illustrates the application of substr along with find(). In this case, find() is employed to identify the ‘@’ within the string, then it utilizes the substr() function to capture everything that follows it.
2. Substring Prior to a Character
Here, we shall define the string that exists before the designated character. In C++, you can leverage the find() function to ascertain the location of that character and subsequently apply substr(0, pos) to fetch everything preceding it. This is frequently used to extract the username from an email address.
Example:
``````html
Cpp
Code Duplicated!
Output:
The preceding C++ program extracts the segment that appears before the ‘@’ character. It initially utilizes find() to identify the ‘@’ and then applies the substr(0, pos) function to retrieve the relevant username. The ultimate output, “user,” appears on your console.
3. Display All Substrings
It generates and displays all possible substrings of the specified string. In C++, this is commonly achieved with two nested loops: The first one determines the starting position, while the second sets the length. This method proves beneficial for searching, analyzing, and matching patterns within a string.
function closeOutput52045() {
var code = editor52045.getSession().getValue();
jQuery(".maineditor52045 .code-editor-output").hide();
}
// Assign event handlers to the buttons
document.getElementById("copyBtn52045").addEventListener("click", copyCodeToClipboard52045);
document.getElementById("runBtn52045").addEventListener("click", runCode52045);
document.getElementById("closeoutputBtn52045").addEventListener("click", closeOutput52045);
Output:
This C++ code is designed to output all substrings of the string abc. It employs two nested loops: the outer loop (i) establishes the starting index of the substring, while the inner loop (j) determines the fixed length of the substring commencing from that index. We call the substr(i,j) function to generate and display every substring. For instance, with “abc”, the results would include: “a”, “ab”, “abc”, “b”, “bc”, “c.”
4. Retrieve Maximum and Minimum Values of All Substrings Representing a Number
This method involves extracting all valid substrings from a given digit string and returning the highest and lowest ones. To achieve this in C++, you can loop through all potential substrings, convert them to integers using stoi(), and compare the values to track the minimum and maximum. This technique is useful for tackling problems related to numeric analysis or pattern detection.
Example:
Cpp
Code Copied!
var isMobile = window.innerWidth ");
editor60093.setValue(decodedContent); // Set the default text
editor60093.clearSelection();
editor60093.setOptions({
maxLines: Infinity
});
function decodeHTML60093(input) {
var doc = new DOMParser().parseFromString(input, "text/html");
return doc.documentElement.textContent;
}
// Function to copy code to clipboard
function copyCodeToClipboard60093() {
const code = editor60093.getValue(); // Get code from the editor
navigator.clipboard.writeText(code).then(() => {
// alert("Code copied to clipboard!");
function closeOutput60093() {
var code = editor60093.getSession().getValue();
jQuery(".maineditor60093 .code-editor-output").hide();
}
// Assign event handlers to the buttons
document.getElementById("copyBtn60093").addEventListener("click", copyCodeToClipboard60093);
document.getElementById("runBtn60093").addEventListener("click", runCode60093);
document.getElementById("closeoutputBtn60093").addEventListener("click", closeOutput60093);
Output:
This C++ program retrieves the highest and lowest numeric values from all substrings of the string “8347.”
``````html
It employs nested loops to construct every potential substring, converts it to an integer via stoi(), and subsequently modifies the maximum and minimum values. As a result, it shows the highest and lowest values derived from the digits of any string.
Identify Overlapping Substrings Utilizing substr() in C++
In a string, overlapping substrings manifest multiple times within the same string and may share certain characters. Unlike straightforward repetition, overlapping signifies that the conclusion of one occurrence may coincide with the commencement of another.
Clarification:
Receives a primary string and a target substring.
Cycles through the primary string with a loop.
Compares at each index a substring whose length matches that of the target.
Moves the index ahead by 1 position to facilitate overlapping.
Illustration:
Cpp
Code Copied!
var isMobile = window.innerWidth ");
editor61736.setValue(decodedContent); // Set the default text
editor61736.clearSelection();
editor61736.setOptions({
maxLines: Infinity
});
function decodeHTML61736(input) {
var doc = new DOMParser().parseFromString(input, "text/html");
return doc.documentElement.textContent;
}
// Function to copy code to clipboard
function copyCodeToClipboard61736() {
const code = editor61736.getValue(); // Get code from the editor
navigator.clipboard.writeText(code).then(() => {
// alert("Code copied to clipboard!");
function closeoutput61736() {
var code = editor61736.getSession().getValue();
jQuery(".maineditor61736 .code-editor-output").hide();
}
// Attach event listeners to the buttons
document.getElementById("copyBtn61736").addEventListener("click", copyCodeToClipboard61736);
document.getElementById("runBtn61736").addEventListener("click", runCode61736);
document.getElementById("closeoutputBtn61736").addEventListener("click", closeoutput61736);
Output:
The example input consists of a text and a pattern, and we are tasked with finding the overlapping substrings in the text; this pattern will aid us in resolving that issue. If a match is found, it increments the counter. In the “ababab” string, “ab” was located at positions (0, 2, 4), yielding a return count of 3. The program then outputs the total count.
Utilizations of substr() in C++
CSV or TSV Parsing – A prevalent method in numerous data processing tasks, where strings are divided by commas or tabs, and distinct fields must be extracted.
Log File Examination – Analyzing structured log entries to capture timestamps, log levels, and messages.
Frequently utilized to produce diagnostics, overviews, or shortened representations of lengthy strings for display in user interfaces.
Data Masking – Employing division and substitution at certain points of sensitive information, such as credit card numbers or telephone numbers.
Longest Palindromic Substring – Determines if a specified substring is a palindrome.
Sliding Window Technique – In a loop, it generates fixed-size substrings beneficial for problems related to pattern searches or hashing.
Conclusion
String manipulation is a crucial aspect of C++, and the substr() function serves as an excellent means to create substring subsets from your strings. Use cases involve data parsing, text processing, and algorithmic challenges. A substr() simplifies and enhances string handling, extending from basic string slicing and trimming to intricate tasks, like log analysis and pattern recognition. Mastering substr() is vital for effective string manipulation in contemporary C++ applications.
Substring in C++ – FAQs
``````html
Q1. What is the purpose of the substr() function in C++?
It extracts a portion of a string beginning from a specified position, with an optional length parameter.
Q2. What occurs if the length argument is omitted in substr()?
The substring will encompass all characters from the starting index to the conclusion of the string.
Q3. Is it possible for substr() to throw an exception in C++?
Indeed, it may throw std::out_of_range when the starting index exceeds the length of the string.
Q4. Does substr() use zero-based indexing?
Yes, substr() implements zero-based indexing for its starting position.
Q5. Is it possible to use substr() directly with string literals?
No, substr() cannot be utilized directly on a string literal. You must first convert it into an std::string.
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