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C++
  • 1. C++ Basics
    • 1.1 Input, Output, and Program Structure
      • 1.1.1 Welcome to Data Structures in C++
      • 1.1.2 Hello World
      • 1.1.3 Input and Output
      • 1.1.4 getline and cin
      • 1.1.5 Program Structure
    • 1.2 Basic Data Types
      • 1.2.1 Basic Data Types
        • 1.2.1.1 Differences between C++ and Java Data Types and Variables
      • 1.2.2 Strings and Characters
      • 1.2.3 Numbers
      • 1.2.4 Booleans
    • 1.3 Conditional Statements
      • 1.3.1 Conditional Statements
      • 1.3.2 Basic If/Else Statements
      • 1.3.3 Comparing Strings
      • 1.3.4 Logical Operators
    • 1.4 Loops
      • 1.4.1 Loops
      • 1.4.2 For Loops
      • 1.4.3 While Loops
      • 1.4.4 Searching a String
    • 1.5 Functions in C++
      • 1.5.1 Functions in C++
      • 1.5.2 Defining and Calling Functions
      • 1.5.3 Passing by Reference vs Value
      • 1.5.4 Function Prototypes
  • 2. Going Beyond the Basics
    • 2.1 Vector Basics
      • 2.1.1 Vector Basics
      • 2.1.2 Creating and Accessing Vectors
      • 2.1.3 Inserting into a Vector
      • 2.1.4 Looping Through a Vector
    • 2.2 Function Default Values
      • 2.2.1 Function Default Values
      • 2.2.2 Default Values
      • 2.2.3 Default Values with a Prototype
      • 2.2.4 Example: Splitting a String
    • 2.3 Structs
      • 2.3.1 Structs
      • 2.3.2 Defining and Accessing Structs
      • 2.3.3 Using Structs: Line Length
    • 2.4 File Input/Output
      • 2.4.1 File Input/Output
      • 2.4.2 Reading in a File
      • 2.4.3 Processing a File
      • 2.4.4 Writing to a File
      • 2.4.5 Creating an Input Stream from a String
    • 2.5 Error Handling
      • 2.5.1 Error Handling
      • 2.5.2 Validating a Number
      • 2.5.3 Validating a Vector Index
      • 2.5.4 Throwing Other Values
  • 3. Libraries
    • 3.1 Header Files
      • 3.1.1 Header Files
      • 3.1.2 Header File
      • 3.1.3 Header and Implementation File
      • 3.1.4 Safer Header
    • 3.2 Using Libraries
      • 3.2.1 Using a Utilities Library
      • 3.2.2 The Util Library
  • 4. 2D Vectors, Stacks, and Queues
    • 4.1 2D Vectors
      • 4.1.1 2D Vectors
      • 4.1.2 The 2D Vector
      • 4.1.3 Creating a 2D Vector
    • 4.3 Stacks
      • 4.3.1 Stacks
      • 4.3.2 Basic Stack
      • 4.3.3 Stack Example: Reverse a String
    • 4.5 Queues
      • 4.5.1 Queues
      • 4.5.2 Basic Queues
      • 4.5.3 Queue Example: Next in Line
  • 5. Sets and Maps
    • 5.1 Pairs and Iterators
      • 5.1.1 Pairs and Iterators
      • 5.1.2 Pairs
      • 5.1.3 Iterators
    • 5.3 Sets
      • 5.3.1 Sets
      • 5.3.2 Basic Sets
      • 5.3.3 Iterating Through a Set
      • 5.3.4 Sets of Struct Values
    • 5.4 Maps
      • 5.4.1 Maps
      • 5.4.2 Map Basics
      • 5.4.3 Iterating Through a Map
      • 5.4.4 Updating Maps
  • 6. Recursion
    • 6.1 Functional Recursion
      • 6.1.1 Functional Recursion
      • 6.1.2 Basic Recursive Problem: Exponential
      • 6.1.3 Recursion Example: Reverse String
      • 6.1.4 Recursion Example: Make Sum
    • 6.2 Procedural Recursion
      • 6.2.1 Procedural Recursion
      • 6.2.2 Print Binary
      • 6.2.3 Print Permutations
      • 6.2.4 Depth vs Breadth Search
  • 7. Pointers, Linked Lists, and Graphs
    • 7.1 Pointers
      • 7.1.1 Pointers
      • 7.1.2 Assigning and Updating Pointers
      • 7.1.3 Pointers and Functions
      • 7.1.4 Pointers and Data Structures
    • 7.2 Linked Lists
      • 7.2.1 Linked Lists
      • 7.2.2 Basic Linked List
      • 7.2.3 Linked List and Recursion
      • 7.2.4 Example: Sorted Phone Book
      • 7.2.5 Doubly Linked List
    • 7.3 Graphs
      • 7.3.1 Graphs
      • 7.3.2 Basic Example: Breadth First Search
      • 7.3.3 Application: Connecting Cities
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  • Find Command
  • Assigning a Value While Evaluating
  • Try This Example
  1. 1. C++ Basics
  2. 1.4 Loops

1.4.4 Searching a String

Like other languages, C++ allows us to search a string for a value, however the syntax is a little different compared to languages like Java.

Find Command

In C++, you use the find command to search a string. If the string is found, the position where the first instance is found is returned.

When the string is not found, the string no position value is returned. This value is represented as string::npos.

Here is an example of the syntax to search for a cat.

string str = "alley cat";
if(str.find("cat") != string::npos) {
    cout << "I found a cat!" << endl;
}

Assigning a Value While Evaluating

One of the more unique features of C++ is that you can assign a value in the same statement that you evaluate it. This allows you to combine statements in a logical way. For example, if you wanted to find whether a phrase contained cat and print the position only if it does, you can do something like this:

int found;
if((found = str.find("cat")) != string::npos) {
    cout << "I found a cat at position ";
    cout << found << endl;
}

Notice that the variable was declared before the conditional statement and the variable assignment is in parenthesis so that it is created before evaluating.

Try This Example

Previous1.4.3 While LoopsNext1.5 Functions in C++

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