1. Arrays

2. Lab task #1: loops Use your week 1 code (odd or even?) as the baseline
You can use our code sample if you don’t have one
User must be able to enter multiple numbers without restarting the program
User must be able to exit the program when they desire to do so
Tips:
Place the functional part of your code in a loop
Place a prompt in that loop so user can decide when to stop
The loop must only be stopped once the user says so – do not count iterations!
Use either the loop condition or break statement to stop the loop
2018
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3. From code to a runnable program
Preprocessor
Deals with trigraphs, macros, line splicing
Compiler
Creates assembly code
Assembler
Creates object code that is machine runnable
Linker
Creates links to other library functions – e.g. where is printf?
2018
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4. #define macros (preprocessor directives)
#define macros are processed before compilation (preprocessor)
Uses “find and replace” principle
Positioned right after #include statements
#define <name> <expression>
#define SIZE 7
#define TEXTFIELD_LEN 30
#define OPTIONS "settings.ini"
Purpose for now: removing magical numbers, using constants
Unlike variables, these cannot be changed during runtime!
2018
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5. The array data structure
Array is a collection of elements, that have the same data type
Integers (int)
Floating point numbers (float, double)
Characters (char) // character array is also known as a string
etc.
Array elements are indexed using integers, starting from zero
Accessing a member in the array is done by using its index
1-dimensional arrays are also known as vectors
2-dimensional arrays are also known as matrixes
2018
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6. Declaring an array
The size of an array is set at the time of declaration by the number in the square brackets
int numbers[10]; // an array for 10 integers
char textField[15]; // array for chars
The arrays can be N-dimensional and the lengths of the dimensions may vary
int elements[N][M][K];
2018
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7. 1-dimentional array (vector)
When declaring, the number in the square brackets defines array size
int numbers[5];
When accessing a member of the array, we specify the index of the element in the square brackets
numbers[index]
To print out the third element of an array we would use:
printf("%d", numbers[2]);
numbers[0]
numbers[1]
numbers[2]
numbers[3]
numbers[4]
2018
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8. Sample 1: Arrays #include <stdio.h> #define NUM_COUNT 3
#define NUM_COUNT 3
int main(void) {
int scoreTable[NUM_COUNT];
scoreTable[0] = 93;
scoreTable[1] = 85;
scoreTable[2] = 51;
printf("The students achieved the following results: %d, %d and %d\n",
scoreTable[0], scoreTable[1], scoreTable[2]);
return 0; }
2018
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9. Sample 2: arrays and loops
#include <stdio.h> #define NUM_COUNT 5 int main(void) { int numArr[NUM_COUNT] = {19, 2, -5, 133, 0}; int i; printf("The numbers stored in the array are:\n"); for (i = 0; i < NUM_COUNT; i++) printf("%d\n", numArr[i]); } return 0;
2018
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10. Homework for next week
Model 2 algorithms in UML: one using loops and one without
Client wishes to withdraw cash from an ATM. Read the desired amount, validate it and output using the minimum amount of bank notes
945€ -> 1x500€, 2x200€, 2x20€, 1x5€
Write a program in C
Client wishes to withdraw cash from an ATM. Read the desired amount, validate it and output using the maximum number of unique bank notes
945€ -> 1x500€, 1x200€, 1x100€, 1x50€, 1x20€, 1x10€, 13x5€
Validate! Both 103€ and -20€ should trigger an error.
There’s a pseudocode to help you!
2018
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11. Lab task #2: finding min, max – UML
The following task must be modelled in UML!
User will enter 5 numbers from the keyboard
The program will find the minimum and maximum value from those numbers
The program will print out the original array
The program will print out the minimum and maximum values from that array
2018
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12. Lab task #2: finding min, max – code
Create a program based on the algorithm composed previously (slight alterations!)
User will input 5 numbers. Those numbers are stored in an array
After input, the following result will be printed on the screen:
The list of the numbers that were entered
The smallest number and the index of that number
The biggest number and the index of that number
If either the smallest or the biggest number is entered multiple times, display the last occurrence
2018
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13. Advanced tasks Task 1: Task 2: Task 3: Use a suitable formatting
Find the minimum and maximum value in the same loop
Find the arithmetic mean, sum and product of the given numbers
Task 2:
If the min/max value is present multiple times, display all of the positions
Task 3:
Allow the user to specify how many numbers will be entered
The absolute maximum is set to 50 numbers
Limit the user’s input so that the user couldn’t overflow the array
2018
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