2.4 - Common String Functions (from <cstring> library)
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Introduction & Overview
Read summaries of the section's main ideas at different levels of detail.
Quick Overview
Standard
The section covers common string functions such as strlen, strcpy, strcat, and strcmp. It explains how each function operates on strings and provides examples to demonstrate their use.
Detailed
Common String Functions (from
This section introduces several vital string functions provided by the <cstring> library in C++. These functions allow for fundamental operations on strings, facilitating their manipulation in programs. Understanding how to use these functions is crucial for effective string processing, which plays a significant role in data handling and text operations in programming.
Key Functions
- strlen(str): Returns the length of the string excluding the null character.
- Example: `strlen(
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Function Descriptions
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Function Description
strlen(str) Returns length of the string
strcpy(dest, src) Copies one string into another
strcat(str1, str2) Concatenates two strings
strcmp(str1, str2) Compares two strings lexicographically
Detailed Explanation
In C++, the
1. strlen(str): This function returns the length of a string without counting the null character at the end of the string.
2. strcpy(dest, src): This function copies the contents of the source string (src) into the destination string (dest).
3. strcat(str1, str2): This function concatenates (appends) the second string (str2) to the end of the first string (str1).
4. strcmp(str1, str2): This function compares two strings lexicographically, meaning it checks their alphabetical order.
Examples & Analogies
Think of the string functions as tools in a toolbox. Just as you might have one tool to measure a length (like a ruler), another tool to copy a design (like a photocopier), a mechanism to attach one object to another (like glue), and a scale to compare weights (like a weighing scale), these string functions help you manage and manipulate strings in programming effectively.
Example of String Concatenation
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Chapter Content
Example
cpp
char str1[20] = "Hello";
char str2[20] = "World";
strcat(str1, str2); // str1 becomes "HelloWorld"
Detailed Explanation
In this example, we declare two character arrays (strings):
- str1 is initialized with "Hello" and
- str2 is initialized with "World". By using the strcat() function, we concatenate str2 to str1. After this operation, str1 will hold the value "HelloWorld". This demonstrates how string functions can modify existing strings by combining them.
Examples & Analogies
Imagine you have a first name 'Hello' written on a piece of paper and a last name 'World' on another piece of paper. If you want to merge them to form a full name 'HelloWorld', you take the two pieces of paper and write them down on one sheet together. That's like what strcat() does for strings in your code.