What are primary data types in C language?

Primary data types, also known as fundamental data types, are built-in data types in C programming language. The C compiler supports four fundamental data types that serve as the building blocks for storing and working with different kinds of data −

• Integer − for whole numbers
• Character − for single characters
• Float − for decimal numbers
• Double − for high-precision decimal numbers

Syntax

// Declaration syntax for primary data types
int variable_name;
char variable_name;
float variable_name;
double variable_name;

Integer Data Type

Integer data types store whole numbers (positive or negative) without decimal points. They come in different sizes to accommodate various ranges of values −

Example

#include <stdio.h>

int main() {
    int num = 100;
    unsigned int uNum = 200;
    short int sNum = -50;
    long int lNum = 1000000;
    
    printf("Integer: %d<br>", num);
    printf("Unsigned Integer: %u<br>", uNum);
    printf("Short Integer: %hd<br>", sNum);
    printf("Long Integer: %ld<br>", lNum);
    
    return 0;
}

Integer: 100
Unsigned Integer: 200
Short Integer: -50
Long Integer: 1000000

Character Data Type

Character data types store single characters and are internally represented as integers using ASCII values. Each character occupies 1 byte of memory −

Example

#include <stdio.h>

int main() {
    char ch = 'A';
    unsigned char uCh = 'B';
    
    printf("Character: %c<br>", ch);
    printf("Unsigned Character: %c<br>", uCh);
    printf("ASCII value of %c: %d<br>", ch, ch);
    printf("ASCII value of %c: %d<br>", uCh, uCh);
    
    return 0;
}

Character: A
Unsigned Character: B
ASCII value of A: 65
ASCII value of B: 66

Float Data Type

Float data types store decimal numbers with single precision. They are useful for calculations requiring fractional values −

Example

#include <stdio.h>

int main() {
    float pi = 3.14159f;
    float temperature = -12.5f;
    
    printf("Pi value: %.2f<br>", pi);
    printf("Temperature: %.1f°C<br>", temperature);
    printf("Pi with 5 decimals: %.5f<br>", pi);
    
    return 0;
}

Pi value: 3.14
Temperature: -12.5°C
Pi with 5 decimals: 3.14159

Double Data Type

Double data types provide double precision for storing decimal numbers with higher accuracy than float −

Example

#include <stdio.h>

int main() {
    double pi = 3.141592653589793;
    double scientific = 1.23e-4;
    
    printf("Pi (double): %.15lf<br>", pi);
    printf("Scientific notation: %.6lf<br>", scientific);
    printf("Comparison - float vs double:<br>");
    printf("Float pi: %.7f<br>", (float)pi);
    printf("Double pi: %.15lf<br>", pi);
    
    return 0;
}

Pi (double): 3.141592653589793
Scientific notation: 0.000123
Comparison - float vs double:
Float pi: 3.1415927
Double pi: 3.141592653589793

Conclusion

Primary data types in C provide the foundation for all programming operations. Choose int for whole numbers, char for characters, float for basic decimal calculations, and double for high-precision arithmetic. Understanding their memory requirements and ranges helps write efficient and accurate programs.