- C++ Programming Examples
- C++ Programming Examples
- C++: Hello World
- C++: Get Input
- C++: Print Integer
- C++: Add two numbers
- C++: Add, Sub, Multiply, Div
- C++: Add Digits
- C++: Find Average and Percentage
- C++: Find Arithmetic Mean
- C++: Sum of n Natural Numbers
- C++: Sum of n Numbers
- C++: Square's Area and Perimeter
- C++: Rectangle's Area and Perimeter
- C++: Triangle's Area and Perimeter
- C++: Area and Circumference
- C++: Find Simple Interest
- C++: Fahrenheit to Celsius
- C++: Celsius to Fahrenheit
- C++: Print Prime Numbers
- C++: Reverse a Number
- C++: Swap Two Numbers
- C++: Print Multiplication Table
- C++: Find Factorial of a Number
- C++: Find Factors of a Number
- C++: Find HCF and LCM
- C++: Create a Calculator
- C++: Count Digits in a Number
- C++: First and Last Digit Sum
- C++: Product of Number Digits
- C++: Sum of Squares of Digits
- C++: Interchange Digits of Number
- C++ if-else Programs
- C++: Check Even or Odd
- C++: Check Prime or Not
- C++: Check Alphabet or Not
- C++: Check Vowel or Not
- C++: Check Leap Year or Not
- C++: Check Reverse equals Original
- C++: Check Perfect Number
- C++: Check Palindrome or Not
- C++: Check Armstrong or Not
- C++: Divisibility Test
- C++: Find Labor Wage
- C++: Find Discounted Price
- C++: Find Shipping Charge
- C++: Find Telephone Bills
- C++: Calculate Student Grade
- C++: Largest of Two Numbers
- C++: Largest of Three Numbers
- C++ Number Conversion
- C++: Decimal to Binary
- C++: Decimal to Octal
- C++: Decimal to Hexadecimal
- C++: Binary to Decimal
- C++: Binary to Octal
- C++: Binary to Hexadecimal
- C++: Octal to Decimal
- C++: Octal to Binary
- C++: Octal to Hexadecimal
- C++: Hexadecimal to Decimal
- C++: Hexadecimal to Binary
- C++: Hexadecimal to Octal
- C++ Pattern Programs
- C++: Pattern Programs
- C++: Print Diamond Pattern
- C++: Print Floyd's Triangle
- C++: Print Pascal's Triangle
- C++ Array Programs
- C++: 1D Array Program
- C++: Linear Search
- C++: Binary Search
- C++: Largest Element in an Array
- C++: Smallest Element in an Array
- C++: Find Second Largest Element
- C++: Find Second Smallest Element
- C++: Sum of All Elements
- C++: Multiply All Elements
- C++: Element in Even Position
- C++: Element in Odd Position
- C++: Print Even Numbers in Array
- C++: Print Odd Numbers in Array
- C++: Count Even or Odd Numbers
- C++: Sum of Even or Odd Numbers
- C++: Count Positive, Negative, Zero
- C++: Reverse an Array
- C++: Insert an Element
- C++: Delete an Element
- C++: Merge two Arrays
- C++: Bubble Sort
- C++: Selection Sort
- C++: Insertion Sort
- C++: Common Elements
- C++: 2D Array Programs
- C++: Add Two Matrices
- C++: Subtract Two Matrices
- C++: Transpose Matrix
- C++: Multiply Two Matrices
- C++: 3D Array Programs
- C++ String Programs
- C++: Print String
- C++: Find String Length
- C++: Compare Two Strings
- C++: Copy String
- C++: String Concatenation
- C++: Reverse a String
- C++: Delete Vowels from a String
- C++: Delete a Word from a String
- C++: Count Characters in a String
- C++: Count Words in a String
- C++: Frequency of Words
- C++: Remove Spaces from Strings
- C++: Sort a String
- C++: Uppercase to Lowercase
- C++: Lowercase to Uppercase
- C++: Swap Two Strings
- C++: Check the Anagram or Not
- C++: Capitalize All Words in a String
- C++: Get Numbers from a String
- C++ File Programs
- C++: Read a File
- C++: Write Content to a File
- C++: Append Data to a File
- C++: Read and Display File
- C++: Copy a File
- C++: Merge Two Files
- Count Characters in a File
- C++: Capitalize Every Word
- C++: List Files in Directory
- C++: Delete a File
- C++: Encrypt and Decrypt a File
- C++ Misc Programs
- C++: Print ASCII Value
- C++: Add Binary Numbers
- C++: Generate Random Numbers
- C++: Print a Smiling Face
- C++: Days into Years and Months
- C++: Add Two Numbers using Pointer
- C++: Print Fibonacci Series
- C++: Generate Armstrong Numbers
- C++: Find nCr and nPr
- C++: Get IP Address
- C++: Print Date and Time
- C++: Shutdown and Restart Computer
- C++ Programming Tutorial
- C++ Tutorial
C++ Program to Copy One String to Another
In this article, you will learn how to copy one string to another in C++ and get the code for it. The program is created using the following approaches:
- Copy a string without using the strcpy() function
- Using a Pointer, copy a string
- string copy using a user-defined function
- strcpy() is a library function that allows you to copy a string
Copy a string without using the strcpy() function in C++
This program copies the string (entered by the user at run-time) without using any library function like strcpy(). Let's have a look at the program first. Its explanation is given later on.
The question is, "Write a program in C++ that copies one string to another." Here is its answer:
#include<iostream> #include<stdio.h> using namespace std; int main() { char strOrig[100], strCopy[100], i=0; cout<<"Enter the string: "; gets(strOrig); while(strOrig[i]!='\0') { strCopy[i] = strOrig[i]; i++; } strCopy[i] = '\0'; cout<<"\nEntered String: "<<strOrig; cout<<"\nCopied String: "<<strCopy; cout<<endl; return 0; }
This program was built and runs under the Code::Blocks IDE. Here is its sample run:
Now enter the string, say "fresherearth," and press the ENTER key to copy it to another string. Here is the final snapshot of its sample run:
The dry run of the above program with user input of "fresherearth" goes like this:
- Initial value, i=0
- When the user enters the string, say "fresherearth," it gets stored in a variable, strOrig[], in the following way:
- strOrig[0]=c
- strOrig[1]=o
- strOrig[2]=d
- strOrig[3]=e
- strOrig[4]=s
- strOrig[5]=c
- strOrig[6]=r
- strOrig[7]=a
- strOrig[8]=c
- strOrig[9]=k
- strOrig[10]=e
- strOrig[11]=r
- That is, the first character (c) of the string (fresherearth) is stored at the strOrig['s] very first index (0). And the second character (o) gets stored at the second index (1), and so on.
- Because the maximum size of strOrig[] is 100, and the entered string is only 12 characters long, at the 12th index (the index after the last character's index), a null-terminated character (\0) gets automatically initialized. That indicates the end of the string, or that there are no more characters in strOrig from the 12th index.
- Now the condition, strOrig[i]!='\0' or strOrig[0]!='\0' or c!='\0', evaluates to be true, therefore program flow goes inside the loop and the 0th index's character of strOrig[] gets initialized to strCopy[] at the same index.
- That is, strOrig[i] or strOrig[0] or c gets initialized to strCopy[i] or strCopy[0].
- The value of i is now incremented. So i=1
- Program flow goes back and evaluates the condition of the while loop again.
- Because a null-terminated character (\0) is available at the 12th index, both the statements (available in the body of the while loop) gets executed 12 times.
- As a result, each character is copied to the strCopy[] variable one by one.
- When the while loop is finished, don't forgot to initialize a null-terminated character at the index following the last character's index.
- Simply print the values of both variables, strOrig[] and strCopy[].
Copying strings in C++ using a pointer
This program copies the string using a pointer. The question is: write a program in C++ to copy the content of one string to another using a pointer. Here is its answer:
#include<iostream> #include<stdio.h> using namespace std; int main() { char strOrig[100], strCopy[100]; char *origPtr, *copPtr; cout<<"Enter the string: "; gets(strOrig); origPtr = &strOrig[0]; copPtr = &strCopy[0]; while(*origPtr) { *copPtr = *origPtr; origPtr++; copPtr++; } *copPtr = '\0'; cout<<"\nEntered String: "<<strOrig; cout<<"\nCopied String: "<<strCopy; cout<<endl; return 0; }
Here is its sample run with user input: Hello fresherearth
The statement,
origPtr = &strOrig[0];
initializes the strOrig[] variable's initial address. That is its 0th index's address. And the statement,
copPtr = &strCopy[0];
also sets the address of strCopy[] to the 0th.
Note: If a pointer-type variable holds the address of any variable that contains some values, then anything that happens with the variable (pointer) makes changes to the original. because it holds its address, not value. So any operation performed through a pointer-type variable directly effects the value at that address.
The * is called as the value at operator. And & is called as the address of operator.
The statement, origPtr++;
, means that origPtr now holds the next index's address.
So, using the pointer, all of the characters from the original string are copied (one by one) to strCopy[].
Copy a string in C++ using a user-defined function
This program also copies one string to another, but using a user-defined function named cpystr().
#include<iostream> #include<stdio.h> using namespace std; void cpystr(char *, char *); int main() { char strOrig[100], strCopy[100]; cout<<"Enter the string: "; gets(strOrig); cpystr(strOrig, strCopy); cout<<"\nEntered String: "<<strOrig; cout<<"\nCopied String: "<<strCopy; cout<<endl; return 0; } void cpystr(char *origPtr, char *copPtr) { while(*origPtr) { *copPtr = *origPtr; origPtr++; copPtr++; } *copPtr = '\0'; }
This program produces the same output as the previous program.
Copy a string in C++ using the strcpy() function
This is the last program that uses a library function of C++ named strcpy() to copy a string. It takes two strings as its argument. The second argument's value is copied to the first.
#include<iostream> #include<stdio.h> #include<string.h> using namespace std; int main() { char strOrig[100], strCopy[100]; cout<<"Enter the string: "; gets(strOrig); strcpy(strCopy, strOrig); cout<<"\nEntered String: "<<strOrig; cout<<"\nCopied String: "<<strCopy; cout<<endl; return 0; }
The same program in different languages
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