I am a new CS student and am having a hard time understanding 2 dimensional arrays. Right now I am just trying to print it out 1 row at a time.
This is my code
#include <stdio.h>
#define N 3
int main(void)
{
int array[N][N], i, j, rows[N], cols[N];
for(i=0;i<N;i++)
{
printf("Enter row %d: ", i+1);
for(j=0;j<N;j++)
scanf("%d", &array[i][j]);
}
printf("The 5 rows you entered are: \n");
for(i=0;i<N;i++)
{
for(j=0;j<N;j++)
{
printf("%d", array[i][j]);
printf("\n");
}
}
printf("\n");
return 0;
}
I would like to have the program print out:
1 2 3
1 2 3
1 2 3
If I add the \n it prints out:
1\n
2\n
3\n
1\n
2\n
3\n
1\n
2\n
3\n
Imagine the \n's as what the screen is printing out, I am trying to represent what the code prints out. I am having trouble getting this box to print out exactly what I am typing in. It won't let me hit enter over and over to represent what is actually on the command screen.
without the /n it prints out
123123123
I am also trying to add rows and columns. I managed to find some code, and understand most of it, except for one line. This is the code.
#include <stdio.h>
int main(void)
{
int i, j, array[5][5], rows[5],cols[5];
for(i=0;i<5;i++)
{
printf("Enter row %d: ", i+1);
for(j=0;j<5;j++)
scanf("%d", &array[i][j]);
}
**for(i=0;i<5;rows[i]=cols[i]=0,i++);**
for(i=0;i<5;i++)
{
for(j=0;j<5;j++)
{
rows[i]=rows[i]+array[i][j];
cols[j]=cols[j]+array[i][j];
}
}
printf("\nRow Totals: ");
for(i=0;i<5;i++)
printf("%d\t", rows[i]);
printf("\nColumn Totals: ");
for(i=0;i<5;i++)
printf("%d\t", cols[i]);
printf("\n");
return 0;
}
for(i=0;i<5;rows[i]=cols[i]=0,i++);
is the line I do not understand. First off, I don't really understand the rows[i]=cols[i]=0,i++. And second off, I don't understand why there is a semicolon after it. I thought for statements did not use semicolons, but the program does not work correctly without this line, or without the semicolon. When I try to use it without this line of code, it gives me crazy answers, I am assuming because the elements in the array are not set to 0 and this line of code sets the elements of the arrays to 0. Can someone give me another line of code that might be more understandable for someone relatively new to C? And maybe explain to me why it uses a semicolon?
I would like to have the program print out: 1 2 3\n 1 2 3\n 1 2 3\n
Do:
for(i=0;i<N;i++)
{
for(j=0;j<N;j++)
{
printf("%d", array[i][j]);
}
printf("\n");
}
**for(i=0;i<5;rows[i]=cols[i]=0,i++);**
is for sure syntax error. I guess you added ** for marking the statement. However,
for(i=0;i<5;rows[i]=cols[i]=0,i++);
is a valid C statement. A for-loop can be split into the form
for(initilization;condition;increment)
The semi-colon separates the three parts of the for-loop. In your case the for-loop increment part is further divided to multiple statements using commas like below.
for(initialization;condition;do something useful here, update condition variable);
The purpose of the code is to initialize the row and column sums to zero before actually finding the sum. Note the comma in the increment part. It allows you to add multiple statements. Similarly you could use the comma to have multiple initializations or multiple conditions.
The semi-colon after the for-loop is a sequence point. Here, note that you don't have statement/compound-statement for the for-loop. In plain and simple language the semi-colon tells the for-loop to do nothing. But you initialize the row and column sums to zero indirectly inside the for-loop which itself is smart.
It is clear that the usage is not very straight-forward. If you don't understand these kind of statements, I suggest you to go through a good C programming book.