1. Chapter 5: Preparing C Programs

2. Program development Understanding the problem EDIT
Writing an algorithm
Converting to code
COMPILE
RUN
errors
Result
Verifying the algorithm
Chapter 5
Program development

3. Program development pico prog.c cc prog.c a.out Source code EDIT
COMPILE
RUN
errors
Result
Source code
pico prog.c
cc prog.c
a.out
Chapter 5
Program development

4. High-level languages Machine language: computer’s native language.
Add two numbers:
Assembly language: uses mnemonics.
Add two numbers: ADD R1 R2
An assembly code needs to be translated to machine code.
Chapter 5
High-level languages

5. High-level languages
High-level programming languages: bridging the gap between machine language and natural languages.
Examples: COBOL, Fortran, Algol, C
Add two numbers (in C): Z = A + B;
Compilation: translation to machine code.
Chapter 5
High-level languages

6. A C program A sample C program
/* A simple C program to read a number & compute and display
its square by using the multiplication (*) operator. */
#include <stdio.h>
main () /* a C program always has a main function */ {
int n; /* this declares an integer variable 'n' */
printf ("\nEnter the number to be squared: ");
scanf ("%d", &n);
printf ("Using the * operator, the square of %d is %d.\n\n",
n, n*n); }
Chapter 5
A C program

7. Compilation in C Use the cc or gcc compiler: cc prog.c
Produces executable file a.out if no errors
To specify name of executable file, use -o option:
cc -o prog prog.c
Name of executable file becomes ‘prog’.
Chapter 5
Compilation in C

8. Errors Compilation errors: occur during compilation.
Reason: syntax errors.
Easy to rectify.
Run-time errors: occur during execution.
Reasons: logic errors, data errors, computation errors.
Harder to rectify.
Chapter 5
Errors

9. Homework
Try exercises in chapter 5.
Chapter 5
Homework