Arrays, Structure & Union and User defined function in C programming Language

Two-Dimensional Character Array Operations in C,

• A two-dimensional (2D) character array is often used to store and manipulate multiple strings in C.

• Some of the common operations performed on 2D character arrays include:

• Searching an element (character or string)

• Copying strings

• Merging strings

• Finding the length of a given string

• These operations are essential for text processing, name handling, or working with tabular character data.

1. Searching an Element (Character or String).

(A) Searching for a Character in a 2D Character Array.

• To search for a specific character in a 2D array, we loop through all rows and columns.

• Example: Searching for a Character

• #include <stdio.h>

  #define ROWS 3
  #define COLS 10

  int main() {
  char words[ROWS][COLS] = { “Hello”, “World”, “CProg” };
  char searchChar;
  int found = 0;

  printf(“Enter a character to search: “);
  scanf(” %c”, &searchChar);

  for (int i = 0; i < ROWS; i++) {
  for (int j = 0; words[i][j] != ‘\0’; j++) {
  if (words[i][j] == searchChar) {
  printf(“Character ‘%c’ found at row %d, column %d\n”, searchChar, i, j);
  found = 1;
  }
  }
  }

  if (!found) {
  printf(“Character ‘%c’ not found in array.\n”, searchChar);
  }

  return 0;
  }

• The program checks each character and prints its position if found.

(B) Searching for a String in a 2D Character Array.

• To search for a word in a 2D character array, we compare each row with the target string using strcmp().

• Example: Searching for a String

• #include <stdio.h>
  #include <string.h>

  #define ROWS 4
  #define COLS 20

  int main() {
  char names[ROWS][COLS] = { “Alice”, “Bob”, “Charlie”, “David” };
  char searchWord[COLS];
  int found = 0;

  printf(“Enter a string to search: “);
  scanf(“%s”, searchWord);

  for (int i = 0; i < ROWS; i++) {
  if (strcmp(names[i], searchWord) == 0) {
  printf(“String ‘%s’ found at row %d\n”, searchWord, i);
  found = 1;
  break;
  }
  }

  if (!found) {
  printf(“String ‘%s’ not found in array.\n”, searchWord);
  }

  return 0;
  }

• strcmp() is used for string comparison.

• If a match is found, we print the row index.

2. Copying Strings in a 2D Character Array.

• To copy one string into another row of a 2D character array, we use strcpy().

• Example: Copying Strings

• #include <stdio.h>
  #include <string.h>

  #define ROWS 3
  #define COLS 20

  int main() {
  char names[ROWS][COLS] = { “Alice”, “Bob” };
  
  // Copy first string to third row
  strcpy(names[2], names[0]);

  printf(“After copying:\n”);
  for (int i = 0; i < ROWS; i++) {
  printf(“%s\n”, names[i]);
  }

  return 0;
  }

• strcpy(destination, source) copies one row into another.

• No need to manually loop through characters.

3. Merging (Concatenating) Strings.

• To merge two strings from different rows, we use strcat().

• To merge two strings from different rows, we use strcat().

• Example: Merging Two Strings

• #include <stdio.h>
  #include <string.h>

  #define ROWS 3
  #define COLS 40

  int main() {
  char names[ROWS][COLS] = { “Hello”, “World” };
  
  // Merge first and second row into third row
  strcpy(names[2], names[0]); // Copy “Hello”
  strcat(names[2], ” “); // Add space
  strcat(names[2], names[1]); // Append “World”

  printf(“Merged string: %s\n”, names[2]);

  return 0;
  }

• strcpy() initializes the destination.

• strcat() appends another string.

• A space is added manually to separate words.

4. Finding the Length of Strings.

• We use strlen() to determine the length of each string stored in a 2D character array.

• Example: Finding String Lengths

• #include <stdio.h>
  #include <string.h>

  #define ROWS 3
  #define COLS 20

  int main() {
  char words[ROWS][COLS] = { “Programming”, “C Language”, “Code” };

  for (int i = 0; i < ROWS; i++) {
  printf(“Length of ‘%s’: %ld\n”, words[i], strlen(words[i]));
  }

  return 0;
  }

• strlen() counts characters before the null terminator (\0).

• Works efficiently without looping manually.

5. Combining All Operations.

• Here’s a complete program that demonstrates searching, copying, merging, and length finding.

• #include <stdio.h>
  #include <string.h>

  #define ROWS 3
  #define COLS 40

  int main() {
  char words[ROWS][COLS] = { “Hello”, “World” };
  char searchWord[COLS];
  int found = 0;

  // Search for a string
  printf(“Enter a word to search: “);
  scanf(“%s”, searchWord);
  
  for (int i = 0; i < ROWS – 1; i++) {
  if (strcmp(words[i], searchWord) == 0) {
  printf(“String ‘%s’ found at row %d\n”, searchWord, i);
  found = 1;
  }
  }
  if (!found) printf(“String not found.\n”);

  // Copy first string to third row
  strcpy(words[2], words[0]);
  printf(“Copied string: %s\n”, words[2]);

  // Merge first and second string
  strcat(words[2], ” “);
  strcat(words[2], words[1]);
  printf(“Merged string: %s\n”, words[2]);

  // Find length of each string
  for (int i = 0; i < ROWS; i++) {
  printf(“Length of ‘%s’: %ld\n”, words[i], strlen(words[i]));
  }

  return 0;
  }

• Searching: Use strcmp() for full strings and loop for characters.

• Copying: Use strcpy(destination, source).

• Merging: Use strcat(destination, source).

• Finding Length: Use strlen(string).