Difference between Standard I/O Library and ANSI in C

What is ANSI C?

ANSI C refers to the standardized version of the C programming language developed by the American National Standards Institute (ANSI) in 1989. This standard is also called C89 or C90, as it was later adopted by the International Organization for Standardization (ISO).

Before ANSI C, different compilers supported different versions of C. This caused compatibility problems. ANSI solved this by creating a uniform standard that all C compilers could follow.

Key Features of ANSI C:

• A standardized set of keywords and syntax rules.
• A clear definition of data types, operators, and control structures.
• Consistent function prototypes and declarations.
• Portability across platforms and compilers.
• Standard libraries, including stdio.h, stdlib.h, string.h, etc.

So, when you write a program using ANSI C standards, it is more likely to work on any compliant compiler.

What is the Standard I/O Library in C?

The Standard Input/Output (I/O) Library in C is a collection of functions that help a program interact with input and output devices like the keyboard and monitor.

These functions are defined in the stdio.h header file. You include this file in your program to perform basic I/O operations like reading input from the user or printing output to the screen.

Common Standard I/O Functions:

• printf() – Displays output to the console.
• scanf() – Reads formatted input from the keyboard.
• fopen() – Opens a file.
• fclose() – Closes a file.
• getchar() – Reads a single character.
• putchar() – Writes a single character.
• fread() and fwrite() – Read from and write to a file.

These functions make it easy to perform common tasks like showing messages or reading user input without having to interact directly with hardware.

Key Differences Between Standard I/O Library and ANSI C

Example of Standard I/O Library and ANSI in C

#include <stdio.h>  // Standard I/O Library
 
int main() {
    printf("Sanfoundry Certification Quiz Begins!\n");
    return 0;
}

• #include <stdio.h> → From the Standard I/O Library
• Use of int, main, return → Defined by the ANSI C standard

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