Easy tutorial for C / C ++ - Arrays 4 (Two dimensional array)
Two dimensional array :
-
A two-dimensional array can process more data regularly
in the form of a matrix. The basic two-dimensional array declaration method is
as follows.
'Data type' 'array name' ['number of rows'] ['number of
columns']
'Data type': The data type of the data to be stored in the array.
'Array name': The name of the array to be used.
'Number of rows': Number of rows in a two-dimensional array.
'Number of Columns': Number of columns in a two-dimensional array.
'Array name': The name of the array to be used.
'Number of rows': Number of rows in a two-dimensional array.
'Number of Columns': Number of columns in a two-dimensional array.
- Let's look at a simple example.
- Define int a[3][4]. It can be thought of as a matrix of 3 rows and 4 columns
and can store 12 integer data in total. The order of each element data in the
matrix is shown in the following figure.
- Since both rows and columns start at 0, the row index
is 0 to 2, and the column index is 0 to 3. You can use the matrix indices of
each element to assign or return data to each element.
- Let's look at an example.
Example Code
#include
<iostream>
using
namespace std;
int
main(){
int a[3][4] ;
int v ;
v = 0;
cout << "2-dimensional
array" << endl;
for(int i = 0; i < 3; i++){
for(int j = 0; j < 4; j++){
a[i][j] = v ;
v++ ;
}
}
for(int
i = 0; i < 3; i++){
for(int j = 0; j < 4; j++){
cout << " a["
<< i << "][" << j << "] = "
<< a[i][j] << endl;
}
}
return 0;
}
- Declared an integer two-dimensional array 'a'. I declared
an integer type variable 'v' and assigned 0 as an initial value. You want to
assign a value to a two-dimensional array using this 'v' value.
- The first for loops are statements that assign values to
a two-dimensional array. 'i' specifies the row index and 'j' specifies the
column index, and the for loop is implemented. The assignment order is as
follows.
a[0][0],
a[0][1], a[0][2], ... , a[2][3]
- At the beginning a[0][0] is assigned the initial value
0 of v, it is incremented by 1 (v ++), and finally 11 is substituted.
- The second for loop is a syntax that prints out data stored in a
two-dimensional array in the same order.
results
:
2-dimensional
array
a[0][0] = 0
a[0][1] = 1
a[0][2] = 2
a[0][3] = 3
a[1][0] = 4
a[1][1] = 5
a[1][2] = 6
a[1][3] = 7
a[2][0] = 8
a[2][1] = 9
a[2][2] = 10
a[2][3] = 11
- You can see the output in the expected order.
- If you change the output part as follows, you can
output it as a matrix form. You should add "#include <iomanip>"
to the beginning of the program.
for(int
i = 0; i < 3; i++){
for(int j = 0; j < 4; j++){
cout << setw(5) << "a[" << i <<
"][" << j << "]" ;
}
cout << endl;
}
cout << endl;
for(int i = 0; i < 3; i++){
for(int j = 0; j < 4; j++){
cout << setw(10) << a[i][j] ;
}
cout << endl;
}
results
:
2-dimensional
array
a[0][0]
a[0][1] a[0][2] a[0][3]
a[1][0]
a[1][1] a[1][2] a[1][3]
a[2][0] a[2][1] a[2][2]
a[2][3]
0 1 2 3
4 5 6 7
8 9 10 11
No comments:
Post a Comment