C Language Standards

Welcome to the tutorial on C language standards. C is a versatile programming language that has evolved over time, leading to the development of different language standards. In this tutorial, we will explore the various C language standards, their features, and how to write portable C code. Let's get started:

Introduction to C Language Standards

C language standards define the syntax, semantics, and features of the C programming language. They ensure compatibility and provide guidelines for writing portable C code that can be compiled and executed on different platforms. Some of the widely recognized C language standards include ANSI C (C89), ISO C (C90), and C99.

Examples of C Language Standards

Here's an example of a C program written in ANSI C:


#include <stdio.h>

int main() {
printf("Hello, ANSI C!\n");
return 0;
}

And here's an example of a C program written in C99:


#include <stdio.h>

int main() {
printf("Hello, C99!\n");
return 0;
}

Understanding C Language Standards

Each C language standard introduces new features, clarifies existing ones, and defines the behavior of the language. When writing C code, it's important to consider the targeted language standard and its compatibility with the compiler and platform you are using. Here are the steps to ensure portability:

Choose a C language standard that suits your requirements and is supported by your compiler and platform.
Write code that adheres to the chosen standard's syntax, semantics, and features.
Use standard library functions and headers defined in the chosen standard.
Avoid using non-standard or implementation-specific features.
Test and compile your code on different platforms to ensure portability.

Common Mistakes with C Language Standards

Using non-standard language features that are specific to a particular compiler or platform.
Not considering the compatibility of the chosen C language standard with the target platform.
Mixing features from different C language standards, leading to code that is not portable.

Frequently Asked Questions (FAQs)

Q1: What is the difference between ANSI C and ISO C?

A1: ANSI C and ISO C are different names for the same language standard. ANSI (American National Standards Institute) adopted the ISO (International Organization for Standardization) C standard, resulting in the term "ANSI C" or "ISO C" being used interchangeably.

Q2: What is C99?

A2: C99 refers to the C language standard published in 1999. It introduced several new features, such as inline functions, variable-length arrays, and new data types.

Q3: Can I use features from C99 in older versions of the C language standard?

A3: No, features introduced in C99 may not be supported in older versions of the C language standard. It's important to check the compatibility of the chosen C language standard with the compiler and platform.

Q4: Are there any widely used compilers that do not support C99?

A4: Some older compilers may have limited or no support for C99 features. It's recommended to use modern compilers, such as GCC or Clang, that provide better support for C99 and newer language standards.

Q5: How can I check the C language standard supported by my compiler?

A5: You can consult the documentation of your compiler or use compiler-specific command-line options, such as -std=c89 for ANSI C or -std=c99 for C99, to specify the desired language standard.

Summary

In this tutorial, we explored the different C language standards, including ANSI C, ISO C, and C99. We learned that language standards define the syntax, semantics, and features of the C programming language. We discussed the importance of writing portable C code and understanding the compatibility of the chosen language standard with compilers and platforms. Finally, we highlighted common mistakes and provided answers to frequently asked questions related to C language standards. Now, you have a solid understanding of C language standards and can write portable C code.