Variables, Format Specifiers Of C

In C, variables are used to store data values. A variable has a data type, a name, and a value. Here’s a breakdown of variables in C:

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1.Declaring and Initializing Variables

To declare a variable:

data_type variable_name;

    int x;            //declaration

To declare and initialize:

data_type variable_name = value;

    int x;            //declaration
    x = 123;       //initialization

Example:

int age = 25;   // Integer variable
float gpa = 2.05;       //floating point number
char grade = 'C';        //single character
char name[] = "Bro"; //array of characters
float pi = 3.14;  // Floating-point variable

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2.C Format Specifiers

Format specifiers in C are used with functions like printf() and scanf() to specify the type of data being printed or read.

1. Integer Format Specifiers

Specifier	Description	Example
%d or %i	Signed integer (decimal)	printf("%d", 42);
%u	Unsigned integer	printf("%u", 42);
%o	Octal integer	printf("%o", 42); → 52
%x	Hexadecimal (lowercase)	printf("%x", 42); → 2a
%X	Hexadecimal (uppercase)	printf("%X", 42); → 2A

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2. Floating-Point Format Specifiers

Specifier	Description	Example
%f	Floating-point (decimal notation)	printf("%f", 3.14159); → 3.141590
%.nf	Fixed decimal places (n digits)	printf("%.2f", 3.14159); → 3.14
%e or %E	Scientific notation	printf("%e", 3.14159); → 3.141590e+00
%g or %G	Shortest representation (%f or %e)	printf("%g", 3.14159); → 3.14159

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3. Character & String Format Specifiers

Specifier	Description	Example
%c	Character	printf("%c", 'A'); → A
%s	String	printf("%s", "Hello"); → Hello

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4. Pointer Format Specifier

Specifier	Description	Example
%p	Prints memory address	printf("%p", ptr);

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5. Miscellaneous

Specifier	Description	Example
%%	Prints%	printf("%%"); → %

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6. Width & Precision Modifiers

You can control the width and precision of output.

• Width (%mX): Specifies minimum width.
• Precision (%.nX): Controls decimal places for floating points.

Example:

printf("%10d", 42);   // Output: "        42" (right-aligned)
printf("%-10d", 42);  // Output: "42        " (left-aligned)
printf("%.2f", 3.14159); // Output: "3.14"

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7. Example Program

#include <stdio.h>

int main() {
    int num = 42;
    float pi = 3.14159;
    char ch = 'A';
    char str[] = "Hello";
    char name[] = "Bro"; //array of characters
    char grade = 'C';        //single character
    float gpa = 2.05;       //floating point number

    printf("Integer: %d\n", num);
    printf("Float: %.2f\n", pi);
    printf("Character: %c\n", ch);
    printf("String: %s\n", str);
    printf("Hexadecimal: %x\n", num);
    printf("Pointer: %p\n", (void*)&num);
    printf("Hello %s\n", name);
    printf("Your average grade is %c\n", grade);
    printf("Your gpa is %f\n", gpa);

    return 0;
}