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Arrays and strings are fundamental data structures in C programming. This tutorial will cover the key concepts and operations related to arrays and strings in C.
Arrays are collections of elements of the same data type. They allow you to store and manipulate multiple values efficiently.
Here are some characteristics of C arrays:
- Fixed Size: Once the size of an array is defined, it cannot be changed.
- Single Type: All elements in an array must be of the same type.
- Ordered: Elements are stored in contiguous memory locations and can be accessed using an index.
- Zero-indexed: Array indices start from 0.
Declaring and initializing a single-dimensional array:
data_type array_name[size];
data_type array_name[size] = {value1, value2, ..., valueN};Example: example_array.c
#include <stdio.h>
int main() {
int numbers[5] = {1, 2, 3, 4, 5};
printf("Element at index 2: %d\n", numbers[2]);
return 0;
}Declaring and initializing a multi-dimensional array:
data_type array_name[rows][cols];
data_type array_name[rows][cols] = {{value11, value12, ..., value1c}, {value21, value22, ..., value2c}, ..., {valuer1, valuer2, ..., valuerc}};Example: example_multidimension_array.c
#include <stdio.h>
int main() {
int matrix[2][3] = {{1, 2, 3}, {4, 5, 6}};
printf("Element at (1, 2): %d\n", matrix[1][2]);
return 0;
}-
Traversal:
for (int i = 0; i < size; i++) { printf("%d ", array[i]); }
-
Insertion:
array[index] = new_value;
-
Deletion:
for (int i = index; i < size - 1; i++) { array[i] = array[i + 1]; } size--;
Example: example_array_manipulation.c
#include <stdio.h>
int main() {
int numbers[5] = {1, 2, 3, 4, 5};
int size = 5;
printf("Original array: ");
for (int i = 0; i < size; i++) {
printf("%d ", numbers[i]);
}
printf("\n");
// Insert a new element at index 2
numbers[2] = 10;
printf("Array after insertion: ");
for (int i = 0; i < size; i++) {
printf("%d ", numbers[i]);
}
printf("\n");
// Delete the element at index 1
for (int i = 1; i < size - 1; i++) {
numbers[i] = numbers[i + 1];
}
size--;
printf("Array after deletion: ");
for (int i = 0; i < size; i++) {
printf("%d ", numbers[i]);
}
printf("\n");
return 0;
}In C, strings are represented as null-terminated character arrays. They provide various functions for string manipulation.
Here are some characteristics of C strings:
- No Built-in String Type: C does not have a built-in string type. Instead, strings are typically implemented as arrays of characters.
- Null-terminated: C strings are terminated by the null character ('\0'). The null character is not part of the string itself, but it signals the end of the string.
- Single Byte Characters: Each character in a C string occupies a single byte of memory.
- Modifiable: C strings are mutable, meaning you can change their contents.
Image source: https://www.geeksforgeeks.org/strings-in-c/
There are several ways to declare and initialize strings in C:
Declaring a string without initialization:
char string_name[size];Initializing a string with a string literal:
char string_name[] = "string_literal";Initializing a string with individual characters:
char string_name[] = {'c', 'h', 'a', 'r', 's', '\0'};Initializing a string with a single character:
char string_name[size] = {[0 ... size-2] = 'a', [size-1] = '\0'};-
Accessing individual characters:
char c = str[index];
-
Modifying individual characters:
str[index] = 'new_char';
-
Inserting a character:
for (int i = strlen(str); i > index; i--) { str[i] = str[i - 1]; } str[index] = 'new_char';
-
Deleting a character:
for (int i = index; i < strlen(str); i++) { str[i] = str[i + 1]; }
Example: examples_string_manipulation.c
#include <stdio.h>
#include <string.h>
int main() {
char str[20] = "Hello, world!";
printf("Original string: %s\n", str);
// Access individual character
printf("Character at index 7: %c\n", str[7]);
// Modify individual character
str[7] = 'W';
printf("Modified string: %s\n", str);
// Insert a character
int index = 6;
for (int i = strlen(str); i > index; i--) {
str[i] = str[i - 1];
}
str[index] = ' ';
printf("String after insertion: %s\n", str);
// Delete a character
index = 7;
for (int i = index; i < strlen(str); i++) {
str[i] = str[i + 1];
}
printf("String after deletion: %s\n", str);
return 0;
}- strlen(): Determines the length of a string.
- strcpy(): Copies one string to another.
- strcat(): Concatenates two strings.
- strcmp(): Compares two strings.
- strncpy(): Copies a specified number of characters from one string to another.
Example: example_string_handling_functions.c
#include <stdio.h>
#include <string.h>
int main() {
char str1[20] = "Hello";
char str2[20] = ", world!";
char str3[40];
printf("Length of str1: %lu\n", strlen(str1));
strcpy(str3, str1);
strcat(str3, str2);
printf("Concatenated string: %s\n", str3);
if (strcmp(str1, str2) < 0) {
printf("str1 is less than str2\n");
} else {
printf("str1 is greater than or equal to str2\n");
}
return 0;
}Beaking down the code:
-
#include <string.h>: Includes the string library, offering functions for string manipulation, such asstrlen,strcpy,strcat, andstrcmp. -
printf("Length of str1: %lu\n", strlen(str1));: Prints the length of the stringstr1to the console using thestrlenfunction. The%luformat specifier is used for unsigned long integers. -
strcpy(str3, str1);: Copies the contents ofstr1tostr3using thestrcpyfunction. -
strcat(str3, str2);: Concatenatesstr2to the end ofstr3using thestrcatfunction. -
if (strcmp(str1, str2) < 0) { ... } else { ... }: Comparesstr1andstr2using thestrcmpfunction.
Arrays and strings are fundamental data structures in C programming. Understanding how to declare, initialize, and manipulate them is crucial for solving a wide range of programming problems.