Lecture 24 - The C programming. After studying this chapter you will be able to understand: Algorithms and programs, a C programming language, history of C, how to get started with C, basic Structure of a C program, data storage and data types, printf() and scanf() functions and usage precedence, unary operations, increment and decrement operations.
The C Programming Lecture 24 Summary of Previous Lecture Programming Introduction What in real life is Problem Solving? Problem Solving process Algorithm History Working Definition Examples Algorithms to Programs Summary of Previous Lecture Components of Algorithms Variables and values Instructions Sequences Procedures Selections Repetitions Documentation Software Development Process Top Down Algorithm Design Today’s Lecture Algorithms and Programs A C programming language History of C C, A High level language How to get started with C Basic Structure of a C program Data Storage and Data Types Variables, Keywords, identifiers, Assignment Today’s Lecture constant variable printf() and scanf() functions and usage Precedence int and float Unary operations Increment and decrement operations Today’s Lecture Comments Error and its Types Summary From Algorithms to Programs Both are sets of instructions on how to a task Algorithm: talking to humans, easy to understand in plain (English) language Program: talking to computer (compiler) can be regarded as a “formal expression” of an algorithm A C Programming Language Flexible language: Structured language Low level activities possible It can produce lean and efficient code Wide availability on a variety of computers Widely used! History of C CPL Combined Programming Language (Barron et al., 1963) BCPL Basic CPL (Richards, 1969) B (Thompson, 1970) C K&R C (Ritchie, 1972) ANSI C American National Standards Institute C (X3J11, 1989) C99 (JTC1/SC22/WG14, ISO/IEC 9899, 1999) A High-Level Language #include int main() { printf(“Hello World”); return 0; } Source code 10100110 01110110 00100110 00000000 11111010 11111010 01001110 10100110 11100110 10010110 11001110 00101110 10100110 01001110 11111010 01100110 01001110 10000110 etc Executable code Compilers and linkers translate a high level program into executable machine code Example Simple Expressions Evaluate an expression set result to 1+2*3-4/5 output result #include Example Simple Expressions Evaluate an expression #include /* Evaluate an expression */ set result to 1+2*3-4/5 output result Example Simple Expressions Evaluate an expression #include /* Evaluate an expression */ int main() { set result to 1+2*3-4/5 output result return 0; } Example Simple Expressions Evaluate an expression #include /* Evaluate an expression */ set result to 1+2*3-4/5 output result int main() { float result; return 0; } Example Simple Expressions Evaluate an expression #include /* Evaluate an expression */ set result to 1+2*3-4/5 output result int main() { float result; result = + * - / 5; return 0; } Example Simple Expressions Evaluate an expression #include /* Evaluate an expression */ set result to 1+2*3-4/5 output result int main() { float result; result = + * - / 5; printf(“%f\n”, result); return 0; } Example Simple Expressions Evaluate an expression #include /* Evaluate an expression */ set result to 1+2*3-4/5 output result Output: 7.000000 int main() { float result; result = + * - / 5; printf(“%f\n”, result); return 0; } Comments Essential for documenting programs Run from a /* to the next */ Examples: /* THIS IS A COMMENT */ /* So is this /* ** and this ** */ */ Comments Comments not “nest” /* Comments start with a “/*” and end with a “*/” but they don’t nest! */ Errors in C Program Do not get Fear of an Error! All good programmers started with lot of Errors Understand them and remove them! Types of Errors In c program you may get Syntax error Logical error Run time errors Syntax Error These errors occur because of wrongly typed statements, which are not according to the syntax or grammatical rules of the language For example, in C, if you don’t place a semicolon after the statement (as shown below), it results in a syntax error printf(“Hello,world”) Logical Error These errors occur because of logically incorrect instructions in the program Let us assume that in a 1000 line program, if there should be an instruction, which multiplies two numbers and is wrongly written to perform addition This logically incorrect instruction may produce wrong results Detecting such errors are difficult! Run Time Errors These errors occur during the execution of the programs though the program is free from syntax and logical errors Some of the most common reasons for these errors are When you instruct your computer to divide a number by zero When you instruct your computer to find logarithm of a negative number When you instruct your computer to find the square root of a negative integer Summary High level language is converted into computer understandable by a compiler Compiler converts source code into computer understandable code C Programming is a way to program computers It has a syntax It has commands and structure C can not be learnt! It can be understood by implementing it! ... software http://turbo-c.soft32.com/ Install it! Follow the step by step guide for your first program! Turbo C++ IDE Version Click New to open a program window Open a new window for writing a program... integer equivalent specified by its position in the ASCII table (pronounced “as-key”) American Standard Code for Information Interchange Character Representation The ASCII values range from... with a semi-colon (;) #include int main() { printf(“Hello World”); return 0; } Where to store data? A data type is a representation of data that defines a size and valid range for data