Understanding String Length and Pointers
- String length: The number of characters in a string, excluding the null terminator (
\0
). - Pointers: Variables that store memory addresses, enabling efficient string manipulation.
Key Concepts Involved
- Pointer Arithmetic: Incrementing a pointer moves it to the next memory address, allowing traversal through string characters.
- Null Terminator: The character
\0
marks the end of a string, essential for determining its length. - Dereferencing: Accessing the value stored at a memory address pointed to by a pointer.
Step-by-Step Code Breakdown
- Header Inclusion:
C
#include <stdio.h>
- Main Function:
C
int main() {
- Variable Declaration:
C
char str[100]; // Array to store the string
int len = 0; // Variable to hold the string length
char *ptr; // Pointer to the string
- User Input for String:
C
printf("Enter a string: ");
fgets(str, 100, stdin);
- Pointer Initialization:
C
ptr = str; // Point ptr to the beginning of the string
- Loop to Calculate Length:
C
while (*ptr != '\0') {
len++; // Increment length for each non-null character
ptr++; // Move pointer to the next character
}
- Output the Length:
C
printf("Length of the string: %d\n", len);
- Return Statement:
C
return 0;
}
Full Code:
C
#include <stdio.h>
int main() {
char str[100];
int len = 0;
char *ptr;
printf("Enter a string: ");
fgets(str, 100, stdin);
ptr = str;
while (*ptr != '\0') {
len++;
ptr++;
}
printf("Length of the string: %d\n", len);
return 0;
}
Explanation:
stdio.h
provides input/output functions.main
is the program’s entry point.str
array stores the string,len
holds the length, andptr
points to the string.- User input is stored in
str
usingfgets
. ptr
is initialized to point to the start ofstr
.- The
while
loop iterates until the null terminator is encountered. - In each iteration,
len
is incremented to count characters, andptr
is moved to the next character. - The final
len
value represents the string length and is printed.
Conclusion:
This program effectively demonstrates string length calculation using pointers in C. By understanding pointer arithmetic, null terminators, and dereferencing, you can efficiently manipulate strings and explore various string-related tasks in C programming.