C Programming - C Format Specifiers

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C Programming - C Format Specifiers

C Format Specifiers

Format specifiers in C are used in input/output functions like printf() and scanf() to specify the type of data to be displayed or read. They provide a way to define how variables should be formatted or interpreted.

List of Format Specifiers

1. Integer Format Specifiers

2. Floating-Point Format Specifiers

3. Character and String Format Specifiers

4. Pointer Format Specifier

5. Special Format Specifiers

Modifiers for Format Specifiers

Modifiers are used to specify the width or size of the data to be read or displayed.

Length Modifiers

Width and Precision

• Width: Minimum number of characters to print.
• Precision: Specifies the number of digits after the decimal point for floating-point values.

Syntax:

%[flags][width][.precision][length]specifier

Example:

printf("%10d", 42);      // Prints 42 with a width of 10 (right-aligned)
printf("%.2f", 3.14159); // Prints 3.14 (2 digits after decimal)

Examples of Usage

1. Integer

int num = 123;
printf("Decimal: %d\n", num);
printf("Octal: %o\n", num);
printf("Hexadecimal: %x\n", num);

2. Floating-Point

float pi = 3.14159;
printf("Value of pi: %.2f\n", pi); // Prints pi up to 2 decimal places

3. Character and String

char ch = 'A';
char str[] = "Hello, World!";
printf("Character: %c\n", ch);
printf("String: %s\n", str);

4. Pointer

int num = 42;
printf("Memory address: %p\n", &num);

Example Program

#include <stdio.h>
 
int main() {
    int num = 42;
    float pi = 3.14159;
    char ch = 'A';
    char str[] = "Hello";
 
    printf("Integer: %d\n", num);
    printf("Floating-point: %.2f\n", pi);
    printf("Character: %c\n", ch);
    printf("String: %s\n", str);
    printf("Pointer address: %p\n", &num);
 
    return 0;
 
}

Output:

Integer: 42
Floating-point: 3.14
Character: A
String: Hello
Pointer address: 0x7ffeec8c

Key Points

1. Use the appropriate specifier for the variable type to ensure proper formatting.
2. Use precision and width modifiers to control the output appearance.
3. Always match the data type of the variable with the corresponding specifier in printf() or scanf(). Mismatched types can lead to undefined behavior.