• Skip to main content
  • Skip to primary sidebar
  • Skip to secondary sidebar
  • Skip to footer

Computer Notes

Library
    • Computer Fundamental
    • Computer Memory
    • DBMS Tutorial
    • Operating System
    • Computer Networking
    • C Programming
    • C++ Programming
    • Java Programming
    • C# Programming
    • SQL Tutorial
    • Management Tutorial
    • Computer Graphics
    • Compiler Design
    • Style Sheet
    • JavaScript Tutorial
    • Html Tutorial
    • Wordpress Tutorial
    • Python Tutorial
    • PHP Tutorial
    • JSP Tutorial
    • AngularJS Tutorial
    • Data Structures
    • E Commerce Tutorial
    • Visual Basic
    • Structs2 Tutorial
    • Digital Electronics
    • Internet Terms
    • Servlet Tutorial
    • Software Engineering
    • Interviews Questions
    • Basic Terms
    • Troubleshooting
Menu

Header Right

Home » C » Puppetting » How will you define String Processing along with the different String Operations
Next →
← Prev

How will you define String Processing along with the different String Operations

By Dinesh Thakur

String Processing (Storing Strings and String Operations) : In C, a string is stored as a null-terminated char array. This means that after the last truly usable char there is a null, hex 00, which is represented in C by ‘\0’. The subscripts used for the array start with zero (0). The following line declares a char array called str.

C provides fifteen consecutive bytes of memory. Only the first fourteen bytes are usable for character storage, because one must be used for the string terminating null.

char str[15];

The following is a representation of what would be in RAM, if the string “Hello, world!” is stored in this array.

Characters: H e l l o , w o r l d !

Hex values: 48 65 6C 6C 6F 2C 20 77 6F 71 6C 64 21 00

Subscripts: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

The name of the array is treated as a pointer to the array. The subscript serves as the offset into the array, i.e., the number of bytes from the starting memory location of the array. Thus, both of the following will save the address of the 0th character in the pointer variable ptr.

ptr = str;

ptr = &str[0];

strlen()

Syntax: len = strlen(ptr);

where len is an integer and ptr is a pointer to char strlen() returns the length of a string, excluding the null. The following code will result in len having the value 13.

int len;

char str[15];

strcpy(str, “Hello, world!”);

len = strlen(str);

strcpy()

Syntax: strcpy(ptr1, ptr2);

where ptr1 and ptr2 are pointers to char strcpy() is used to copy a null-terminated string into a variable. Given the following declarations, several things are possible.

char S[25];

char D[25];

  • Putting text into a string:
  • strcpy(S, “This is String 1.”);
  • Copying a whole string from S to D:
  • strcpy(D, S);
  • Copying the tail end of string S to D:
  • strcpy(D, &S[8]);

N.B. If you fail to ensure that the source string is null-terminated, very strange and sometimes very ugly things may result.

Strncpy()

Syntax: strncpy(ptr1, ptr2, n);

where n is an integer and ptr1 and ptr2 are pointers to char

strncpy() is used to copy a portion of a possibly null-terminated string into a variable. Care must be taken because the ‘\0’ is put at the end of destination string only if it is within the part of the string being copied. Given the following declarations, several things are possible.

char S[25];

char D[25];

Assume that the following statement has been executed before each of the remaining code fragments.

  • Putting text into the source string:
  • strcpy(S, “This is String 1.”);
  • Copying four characters from the beginning of S to D and placing a null at the end:
  • strncpy(D, S, 4);
  • D[4] = ‘\0’;
  • Copying two characters from the middle of string S to D:
  • strncpy(D, &S[5], 2);
  • D[2] = ‘\0’;
  • Copying the tail end of string S to D:
  • strncpy(D, &S[8], 15);
  • which produces the same result as strcpy(D, &S[8]);

strcat()

Syntax: strcat(ptr1, ptr2);

where ptr1 and ptr2 are pointers to char strcat() is used to concatenate a null-terminated string to end of another string variable. This is equivalent to pasting one string onto the end of another, overwriting the null terminator. There is only one common use for strcat().

char S[25] = “world!”;

char D[25] = “Hello, “;

  • Concatenating the whole string S onto D:
  • strcat(D, S);

N.B. If you fail to ensure that the source string is null-terminated, very strange and sometimes very ugly things may result.

strncat()

Syntax: strncat(ptr1, ptr2, n);

where n is an integer and ptr1 and ptr2 are pointers to char

strncat() is used to concatenate a portion of a possibly null-terminated string onto the end of another string variable. Care must be taken because some earlier implementations of C do not append the ‘\0’ at the end of destination string. Given the following declarations, several things are possible, but only one is commonly used.

char S[25] = “world!”;

char D[25] = “Hello, “;

  • Concatenating five characters from the beginning of S onto the end of D and placing a null at the end:
  • strncat(D, S, 5);
  • strncat(D, S, strlen(S) -1);
  • Both would result in D containing “Hello, world”.

N.B. If you fail to ensure that the source string is null-terminated, very strange and sometimes very ugly things may result.

strcmp()

Syntax: diff = strcmp(ptr1, ptr2);

where diff is an integer and ptr1 and ptr2 are pointers to char

strcmp() is used to compare two strings. The strings are compared character by character starting at the characters pointed at by the two pointers. If the strings are identical, the integer value zero (0) is returned. As soon as a difference is found, the comparison is halted and if the ASCII value at the point of difference in the first string is less than that in the second (e.g. ‘a’ 0x61 vs. ‘e’ 0x65) a negative value is returned; otherwise, a positive value is returned. Examine the following examples.

char s1[25] = “pat”;

char s2[25] = “pet”;

diff will have a negative value after the following statement is executed.

diff = strcmp(s1, s2);

diff will have a positive value after the following statement is executed.

diff = strcmp(s2, s1);

diff will have a value of zero (0) after the execution of the following statement,

which compares s1 with itself.

diff = strcmp(s1, s1);

strncmp()

Syntax: diff = strncmp(ptr1, ptr2, n);

where diff and n are integers ptr1 and ptr2 are pointers to char strncmp() is used to compare the first n characters of two strings. The strings are compared character by character starting at the characters pointed at by the two pointers. If the first n strings are identical, the integer value zero (0) is returned. As soon as a difference is found, the comparison is halted and if the ASCII value at the point of difference in the first string is less than that in the second (e.g. ‘a’ 0x61 vs. ‘e’ 0x65) a negative value is returned; otherwise, a positive value is returned. Examine the following examples.

char s1[25] = “pat”;

char s2[25] = “pet”;

diff will have a negative value after the following statement is executed.

diff = strncmp(s1, s2, 2);

diff will have a positive value after the following statement is executed.

diff = strncmp(s2, s1, 3);

diff will have a value of zero (0) after the following statement.

diff = strncmp(s1, s2, 1);

You’ll also like:

  1. String Processing — Write out a function that prints out all the permutations of a String. For example, abc would give you abc, acb, bac, bca, cab, cba.
  2. Mathematical Operations in Java Example
  3. Set operations Subtraction Java Example
  4. Set operations Intersection Java Example
  5. Set operations Add Java Example
Next →
← Prev
Like/Subscribe us for latest updates     

About Dinesh Thakur
Dinesh ThakurDinesh Thakur holds an B.C.A, MCDBA, MCSD certifications. Dinesh authors the hugely popular Computer Notes blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps.

Dinesh Thakur is a Freelance Writer who helps different clients from all over the globe. Dinesh has written over 500+ blogs, 30+ eBooks, and 10000+ Posts for all types of clients.


For any type of query or something that you think is missing, please feel free to Contact us.


Primary Sidebar

C Programming

C Programming Tutorials

  • C - History
  • C - Anatomy
  • C - Constants
  • C - Identifiers
  • C - Data Types
  • C - Libraries File
  • C - Header Files
  • C - Basic Language
  • C - Data Types Sizes
  • C - Header Files Importance
  • C - Escape Sequences
  • C - Main() Purpose
  • C - Program Procedure
  • C - Control Statements
  • C - Enumeration Constant
  • C - Add numbers
  • C - Return Statement
  • C - Avoid Goto
  • C - Command Line Arguments
  • C - Switch Case
  • C - Switch Case Limitations
  • C - getchar() and putchar()
  • C - Iteration Statements
  • C - Pass by Value and Reference
  • C - Structures and Unions
  • C - Structure
  • C - Dynamic Memory
  • C - Fgets and Fputs Functions
  • C - Gets() and Puts() Functions
  • C - Armstrong Number
  • C - Storage Classes
  • C - Fibonacci Series
  • C - Precision Setting
  • C - const Parameters

C - Variable & It's Type

  • C - Variables
  • C - Variable Lifetime
  • C - Static Variable
  • C - Register Variable
  • C - Global Variables
  • C - Auto Variables
  • C - Local Variables

C - Operator & Expressions

  • C - Operator
  • C - Boolean Operators
  • C - Bitwise Operator
  • C - Arithmetic Operators
  • C - Modulus Operator
  • C - Ternary Operator
  • C - Expressions
  • C - Arithmetic Expressions

C - Array

  • C - Arrays
  • C - Array Types
  • C - Array Characteristics
  • C - Static Arrays
  • C - Global Arrays
  • C - 3D Arrays
  • C - Dynamic Arrays
  • C - Pointer to 3D Arrays
  • C - Array Elements Hold
  • C - Arrays as Function Parameters
  • C - Accessing Matrix Elements
  • C - File Handling
  • C - Matrix Multiplication
  • C - Dynamic Memory Allocation

C - Searching & Sorting

  • C - Data Structures
  • C - Linear Search
  • C - Bubble Sort
  • C - Merge Sort
  • C - Linked List
  • C - Insertion Sort
  • C - Binary Search
  • C - Selection Sort
  • C - Quick Sort

C - Functions

  • C - Functions
  • C - Functions Advantages
  • C - Void Functions
  • C - Function Call
  • C - Default Return Value
  • C - String functions

C - Pointer

  • C - Pointers
  • C - Type Casting Of Pointers
  • C - Pointer Advantages
  • C - Pointers Initialization
  • C - Vectors and Pointers

C - Differences

  • C - C Vs C++
  • C - Formal Args. Vs Actual Args.
  • C - Keywords Vs Identifiers
  • C - Strings Vs Character Arrays
  • C - Address Vs Dereference Operator
  • C - Goto Vs longjmp
  • C - Declaring Vs Defining Variable
  • C - String Vs Array
  • C - Call by Value Vs Reference
  • C - Structure Vs Union
  • C - For Vs While loops
  • C - Compiler Vs Interpreter

C - Programs

  • C Program Standard Deviation
  • C Program Calculate Tax
  • C Program Sum Series
  • C Program Merge Arrays
  • C Program Euclid’s Algorithm
  • C Program Print Weekdays
  • C Program Sum of Digits
  • C Program Print a list
  • C Program Print Pythagorean
  • C Program Quiz program
  • C Program Display Table
  • C Program Print Comma-Separated
  • C Program Prints Prime Numbers
  • C Program for Print Integer
  • C Program Count Number
  • C Program Print Color Name
  • C Program Print Odd Numbers
  • C Program Calculate area
  • C Program for a Menu
  • C Program Add Two Vectors
  • C Program Array Addresses
  • C Program Division by Zero Error
  • C Program Compare two Dates
  • C Program Tower of Hanoi
  • C Program return 3 Numbers
  • C Program for Prime Numbers
  • C Program for Factorial
  • C Program for Palindrome

Other Links

  • C Programming - PDF Version

Footer

Basic Course

  • Computer Fundamental
  • Computer Networking
  • Operating System
  • Database System
  • Computer Graphics
  • Management System
  • Software Engineering
  • Digital Electronics
  • Electronic Commerce
  • Compiler Design
  • Troubleshooting

Programming

  • Java Programming
  • Structured Query (SQL)
  • C Programming
  • C++ Programming
  • Visual Basic
  • Data Structures
  • Struts 2
  • Java Servlet
  • C# Programming
  • Basic Terms
  • Interviews

World Wide Web

  • Internet
  • Java Script
  • HTML Language
  • Cascading Style Sheet
  • Java Server Pages
  • Wordpress
  • PHP
  • Python Tutorial
  • AngularJS
  • Troubleshooting

 About Us |  Contact Us |  FAQ

Dinesh Thakur is a Technology Columinist and founder of Computer Notes.

Copyright © 2025. All Rights Reserved.

APPLY FOR ONLINE JOB IN BIGGEST CRYPTO COMPANIES
APPLY NOW