C Programming Syntax and Conditions

C Programming Study Notes

Syntax

• Basic Structure:
  • Every C program consists of functions, with main() being the entry point.
  • Syntax includes keywords, data types, operators, and control statements.
• Comments:
  • Single-line comments: // comment
  • Multi-line comments: /* comment */
• Semicolons:
  • Statements are typically terminated with a semicolon (;).

If Conditions

• Purpose: Used to execute a block of code based on a condition.
• Basic Syntax:

  if (condition) {
      // code to execute if condition is true
  }
  

Simple If

• Definition: Executes a block of code if the condition evaluates to true.
• Example:

  int x = 10;
  if (x > 5) {
      printf("x is greater than 5");
  }
  

Nested If

• Definition: An if statement inside another if statement.
• Usage: To check multiple conditions sequentially.
• Example:

  if (x > 0) {
      if (x % 2 == 0) {
          printf("x is positive and even");
      } else {
          printf("x is positive and odd");
      }
  }
  

Operators

• Arithmetic Operators: +, -, *, /, %
• Relational Operators: ==, !=, >, <, >=, <=
• Logical Operators: && (AND), || (OR), ! (NOT)
• Assignment Operators: =, +=, -=, *=, /=

Basic C Programs

• Hello World Program:

  #include <stdio.h>
  
  int main() {
      printf("Hello, World!\n");
      return 0;
  }
  

• Program to Check Even or Odd:

  #include <stdio.h>
  
  int main() {
      int num;
      printf("Enter an integer: ");
      scanf("%d", &num);
      if (num % 2 == 0) {
          printf("%d is even\n", num);
      } else {
          printf("%d is odd\n", num);
      }
      return 0;
  }
  

• Simple Calculator:

  #include <stdio.h>
  
  int main() {
      int a, b, sum;
      printf("Enter two integers: ");
      scanf("%d %d", &a, &b);
      sum = a + b;
      printf("Sum: %d\n", sum);
      return 0;
  }
  

C Programming Overview

• C programs consist of functions; main() serves as the entry point for execution.
• Syntax involves keywords, data types, operators, and control statements essential for coding.
• Comments are included for clarity: single-line comments use //, while multi-line comments are enclosed within /* ... */.
• Statements are typically concluded with a semicolon (;), which indicates the end of a command in C.

Conditional Statements

• Conditions are used to execute specific code blocks based on evaluations.

Simple If Statement

• The simple if statement executes a block when the specified condition is true.
• Example demonstrates checking if a variable x is greater than 5, printing a message if true.

Nested If Statement

• A nested if statement allows for multiple conditions to be evaluated sequentially where one if is inside another.
• Example illustrates checking if x is positive, followed by evaluating if it is even or odd, printing appropriate messages based on evaluations.

Operators

• Arithmetic Operators: Used for mathematical operations, including addition (+), subtraction (-), multiplication (*), division (/), and modulus (%) for calculating remainder.
• Relational Operators: Used to compare values, including equality (==), inequality (!=), greater than (>), less than (<), and others for precise conditional evaluations.