Working with Arrays: Definitions and Examples
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1D & 2D Arrays
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CREATE array nums [size]
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<type><name>[size];
For example:
int
size = 10
int
grid[size]
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CREATE array nums [numRows][numColumns]
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<type><name>[<row_size>][<column_size>];
For example:
int
grid[10][20];
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Usually involves nested loops, as shown below.
Problem Statement: Create an array of 4 rows and 5
columns. Populate the array with the numbers 1-20.
---------------------------------------------------------------------
Create array grid[4][5]
count = 1
FOR each element in a row
FOR each element in a column
grid[row][col] = count
count = count + 1
END INNER FOR
END FOR
int count = 1;
int grid[4][5];
//getting the rows in the array
for (int row = 0; row < 4; row++)
{//populate the values in the array (row) we're currently on from the outer loop
for (int column = 0; column < 5; column++)
{grid[row][column] = count;
count++;
}
}
//for each array in the grid (represented by rows)
for (int row = 0; row < 4; row++)
{for (int column = 0; column < 5; column++) {//for each element in the array (row) we're currently on
cout << grid[row][column] << ",";
if(grid[row][column] % 5 == 0) {cout << endl; }
}
}
Pseudocode
– Nested for
Loop
Example
BEGIN MAIN
CREATE
maxRows = 10, row, star
FOR
(row = 1, row < maxRows, row = row + 1)
FOR
(star = 1, star <= row, star = star + 1)
“*”
END
inner
FOR
PRINTLINE ()
END
outer
FOR
END MAIN
Nested for
Loop Example
int
maxRows = 10;
for
(
int
row = 1; row <= maxRows; row++)
{for
(
int
star = 1; star <= row; star++)
{cout <<
"*"
;
}
cout << endl;
}
In this content, you will find detailed explanations and examples on defining and working with 1D and 2D arrays in programming languages like C++. It covers creating arrays, populating them with values, and working with nested loops. The content also includes pseudocode examples for a better understanding of nested loop structures.
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Presentation Transcript
Arrays Arrays 1D & 2D Arrays
Defining a 1D array Defining a 1D array CREATE array nums [size] Ps
C++ C++ - - Define a 1D Array Define a 1D Array <type><name>[size]; For example: int size = 10 int grid[size]
Defining a 2D array Defining a 2D array CREATE array nums [numRows][numColumns] Ps
C++ C++ - - Define a 2D Array Define a 2D Array <type><name>[<row_size>][<column_size>]; For example: int grid[10][20];
Working with 2D arrays Working with 2D arrays Usually involves nested loops, as shown below. Problem Statement: Create an array of 4 rows and 5 columns. Populate the array with the numbers 1-20. --------------------------------------------------------------------- Create array grid[4][5] count = 1 FOR each element in a row FOR each element in a column grid[row][col] = count count = count + 1 END INNER FOR END FOR
int count = 1; int grid[4][5]; //getting the rows in the array for (int row = 0; row < 4; row++) { //populate the values in the array (row) we're currently on from the outer loop for (int column = 0; column < 5; column++) { grid[row][column] = count; count++; } } //for each array in the grid (represented by rows) for (int row = 0; row < 4; row++) { for (int column = 0; column < 5; column++) { //for each element in the array (row) we're currently on cout << grid[row][column] << ","; if(grid[row][column] % 5 == 0) { cout << endl; } } }
Pseudocode Nested for Loop Example BEGIN MAIN CREATE maxRows = 10, row, star FOR (row = 1, row < maxRows, row = row + 1) FOR (star = 1, star <= row, star = star + 1) PRINT * ENDinnerFOR PRINTLINE () ENDouterFOR END MAIN Ps
Nested for Loop Example int maxRows = 10; for (int row = 1; row <= maxRows; row++) { for (int star = 1; star <= row; star++) { cout << "*"; } cout << endl; }
