Format specifier in c

  • What is format specifier ?

    • A format specifier in C is a placeholder used within the format string of functions like 'printf', 'scanf', 'sprintf', and 'sscanf'. It specifies how a particular value should be formatted when it is inputted or outputted. Format specifiers begin with a percent sign ('%'') followed by a character that indicates the type of data to be processed.

  • commonly used format specifier :

    • format specifier description
    %d or %i Used for signed decimal integer.
    %u Used for unsigned decimal integer.
    %o Used for unsigned octal integer.
    %x or %X Used for unsigned hexadecimal integer
    %f Used for decimal floating-point number.
    %e or %E Used for scientific notation
    %c Used for a single character.
    %s Used for a string of characters
    %p Used for printing pointer addresses.
    %% Used to print a literal percent sign ('%').

  • Examples :
    • C Code
    #include<stdio.h> int main() { int b=6; int c=8; printf("Value of b is:%d", b); printf("\nValue of c is:%d",c); }

    Output :
    Value of b is:6
    Value of c is:8

    C Code
    #include<stdio.h> int main() { int a=9; printf("Octal value of a is: %o", a); printf("\nInteger value of a is: %d",a); return 0; }

    Output :
    Octal value of a is: 11
    Integer value of a is: 9

    C Code
    #include<stdio.h> int main() { float y=3.4; printf("Floating point value of y is: %f", y); return 0; }

    Output :
    Floating point value of y is: 3.400000

  • conclusion :

    • Properly using format specifiers in C is fundamental to ensuring program correctness, reliability, and security. It helps prevent bugs, undefined behavior, and vulnerabilities that can arise from incorrect data interpretation. Always double-check and verify that the specifier matches the intended data type to avoid runtime issues in your programs.

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