I am trying to identify the prime and composite value from an array. But in conditional statement, it prints only if value not else.
#include <stdio.h>
int main()
{
int a[5], i, j;
for (i = 0; i < 5; i++)
{
scanf("%d", &a[i]);
}
for (i = 0; i < 5; i++)
{
for (j = 2; j <= a[i] / 2; j++)
{
if (a[i] % j == 0)
{
printf("%d is not a prime number\n", a[i]);
break;
}
else
{
printf("%d is a prime number\n", a[i]);
break;
}
}
}
return 0;
}
The number is prime only if for all for (j = 2; j <= a[i] / 2; j++) the conditional a[i] % j == 0 is false. What you need to do is the following:
#include <stdio.h>
int isNumberPrime(int value){
if(value == 1) return 0;
for (int j = 2; j <= value / 2; j++)
if (value % j == 0)
return 0;
return 1;
}
int main()
{
int a[5];
for (int i = 0; i < 5; i++)
{
scanf("%d", &a[i]);
}
for (int i = 0; i < 5; i++)
{
if(isNumberPrime(a[i]))
printf("%d is a prime number\n", a[i]);
else
printf("%d is not a prime number\n", a[i]);
}
return 0;
}
Related
#include<stdio.h>
int a, b;
float arr[10][10];
void iden(float x[a][b]);
void diag(float x[a][b]);
void pri_sec(float x[a][b]);
int main() {
int i, j, n;
arr[a][b];
for (i = 0;; i++) {
printf("Enter the no. of rows and columns:\n");
scanf("%d %d", &a, &b);
if (a == b) {
printf("Enter the values in an array:\n");
for (i = 0; i < a; i++) {
for (j = 0; j < b; j++)
scanf("%f", &(arr[i][j]));
}
printf("Enter 1 to check it is an identity matrix or not, 2 to check it is diagonal matrix or not\
,3 to check principal and secondary diagonal are equal or not and any other no. to exit:\n");
scanf("%d", &n);
if (n == 1)
iden(arr);
if (n == 2)
diag(arr);
if (n == 3)
pri_sec(arr);
else
return 0;
} else {
printf("It is not a square matrix:\n");
return 0;
}
}
}
void iden(float x[a][b]) {
int i, j, flag = 1;
for (i = 0; i < a; i++) {
for (j = 0; j < b; j++) {
if (x[i][j] != 1 && x[j][i] != 0)
flag = 0;
}
}
if (flag == 1)
printf("It is an identity matrix:\n");
else
printf("It is not an identity matrix:\n");
}
void diag(float x[a][b]) {
int i, j, flag = 0;
for (i = 0; i < a; i++) {
for (j = 0; j < a; j++) {
if ((i == j && x[i][j] == 0) || (i != j && x[i][j] != 0)) {
flag = 1;
break;
}
}
}
if (flag == 0)
printf("It is a diagonal matrix:\n");
else
printf("It is not a diagonal matrix:\n");
}
void pri_sec(float x[a][b]) {
int i, k, flag = 0;
for (i = 0; i < a; i++) {
k = a - 1 - i;
if (x[i][i] != x[i][k]) {
flag = 1;
}
}
if (flag == 1)
printf("The principal and secondary diagonals are not equal:\n");
else
printf("The principal and secondary diagonals are equal:\n");
}
When I changed the indices as 10 10 for the functions it worked but for the other case it didn't.
#include <stdio.h>
int x[10][10];
int ROWS, COLS;
void func_vla(int array[10][10]) {
int i, j;
for (i = 0; i < ROWS; i++) {
for (j = 0; j < COLS; j++) {
array[i][j] = i * j;
}
}
}
int main() {
scanf("%d %d", &ROWS, &COLS);
int x[ROWS][COLS], i, j;
func_vla(x);
for (i = 0; i < ROWS; i++)
for (j = 0; j < COLS; j++)
printf("%d\n", x[i][j]);
}
I want to store elements of maximum and minimum frequency in the arr2 array if there are more than one element of same frequency then both the elements should be stored ? But it is showing wrong results and i am not able to find what is the err. Can anyone help me with this. Any kind of help would be greatly appreciated.
#include <stdio.h>
int main()
{
int n;
scanf("%d", &n);
int arr[n];
for (int i = 0; i < n; i++)
{
scanf("%d", &arr[i]);
}
int arr2[n];
int prevcount = 0;
int k = 0;
// for finding max element
for (int i = 0; i < n; i++)
{
int count = 0;
//counting the number of times it has occured
for (int j = 0; j < n; j++)
{
if (arr[i] == arr[j])
{
count++;
}
}
// checking if the same element was not there in the new array
for (int i = 0; i < k; i++)
{
if (arr[i] == arr[k])
{
goto nextit;
}
}
//it will update the kth element if the count is greater than the prev count
if (prevcount < count)
{
arr2[k] = arr[i];
}
//if these both are same but the number is different then will iterate k by 1 and store that element as well
else if (prevcount == count)
{
k++;
arr2[k] = arr[i];
}
prevcount = count;
nextit:
}
// for finding min element
prevcount = 1000;
for (int i = 0; i < n; i++)
{
int count = 0;
for (int j = 0; j < n; j++)
{
if (arr[i] == arr[j])
{
count++;
}
}
// checking if the same element was not there in the new array if there is then go to the next iteration
for (int i = 0; i < k; i++)
{
if (arr[i] == arr[k])
{
goto nextit2;
}
}
if (prevcount > count)
{
arr2[k] = arr[i];
}
else if (prevcount == count)
{
k++;
arr2[k] = arr[i];
}
prevcount = count;
nextit2:
}
for (int i = 0; i < k; i++)
{
printf("%d ", arr2[i]);
}
return 0;
}
As #SparKot suggests, sorting the array makes the problem simple. Would you please try:
#include <stdio.h>
#include <stdlib.h>
// compare values numerically
int numeric(const void *a, const void *b)
{
return (*(int *)a < *(int *)b) ? -1 : (*(int *)a > *(int *)b);
}
int main()
{
int n, i, j;
int *arr; // input array
int *count; // count frequency: initialized to 0's by calloc
int min = 0; // minimum occurrences
int max = 0; // maximum occurrences
scanf("%d", &n);
if (NULL == (arr = malloc(n * sizeof(int)))) {
perror("malloc");
exit(1);
}
if (NULL == (count = calloc(n, sizeof(int)))) {
perror("calloc");
exit(1);
}
for (i = 0; i < n; i++) {
scanf("%d", &arr[i]);
}
qsort(arr, n, sizeof(int), numeric);
// count the length of sequence of the same numbers
for (i = 0; i < n; i++) {
for (j = 0; i + j < n && arr[i] == arr[i + j]; j++) {
;
}
count[i] = j; // i'th element has length j
i += j - 1; // jump to next number
}
// find minimum and maximum frequencies
for (i = 0; i < n; i++) {
if (count[i]) {
if (min == 0 || count[i] < min) min = count[i];
if (max == 0 || count[i] > max) max = count[i];
}
}
// report the result
for (i = 0; i < n; i++) {
if (count[i] == min) {
printf("min frequency %d value %d\n", count[i], arr[i]);
}
if (count[i] == max) {
printf("max frequency %d value %d\n", count[i], arr[i]);
}
}
return 0;
}
Sample input (n=10):
6
1
2
5
1
2
3
1
3
6
Output:
max frequency 3 value 1
min frequency 1 value 5
Closed. This question is not reproducible or was caused by typos. It is not currently accepting answers.
This question was caused by a typo or a problem that can no longer be reproduced. While similar questions may be on-topic here, this one was resolved in a way less likely to help future readers.
Closed 4 years ago.
Improve this question
I have a C problem where I need to reverse all the numbers on the 5th column of a 2x5 matrix.
So if I have
1 2 3 4 89
3 8 6 8 91
This will become
1 2 3 4 98
3 8 6 8 19
The code I've written so far is:
#include <stdio.h>
void inverse() {
int reversedNumber = 0, remainder, mat[10][10], i, j;
for (i = 0; i < 2; i++)
for (j = 0; j < 5; j++) {
while (mat[i][j] != 0) {
remainder = mat[i][j] % 10;
reversedNumber = reversedNumber * 10 + remainder;
mat[i][j] /= 10;
}
}
printf("Reversed Number = %d", reversedNumber);
}
void main()
{
int mat[10][10], i, j;
printf("Enter your matrix\n");
for (i = 0; i < 2; i++)
for (j = 0; j < 5; j++) {
scanf("%d", &mat[i][j]);
}
printf("\nHere is your matrix:\n");
for (i = 0; i < 2; i++) {
for (j = 0; j < 5; j++) {
printf("%d ", mat[i][j]);
}
printf("\n");
}
inverse(mat[1][5]);
}
After running this I get a ridiculously large number! What should I modify?
There are number of things that can be improved in the code.
First of all you have to set reversedNumber zero inside the innermost loop, this is the reason you get large numbers.
You pass an argument to the function, but the definition is incorrect for the same.
Also, you have stated that you only need to reverse the 5th column, better make call to a function that reverses a single number.
#include<stdio.h>
int inverse(int num) {
int reversednum = 0;
while(num){
reversednum = reversednum*10 + num%10;
num /= 10;
}
return reversednum;
}
void main(){
int mat[10][10],i,j;
printf("Enter your matrix\n");
for(i=0;i<2;i++)
for(j=0;j<5;j++){
scanf("%d",&mat[i][j]);
}
printf("\nHere is your matrix:\n");
for(i=0;i<2;i++){
for(j=0;j<5;j++){
printf("%d ",mat[i][j]);
if(j == 4) mat[i][j] = inverse(mat[i][j]);
}
printf("\n");
}
}
mistakes in your program:
-your function doesnt expect anything i.e empty parameter but you are sending matrix as parameter.
do not unnecessarily use matrix of size [10][10] when your matrix of 2*5
send 'mat' as parameter(i.e address of your matrix) to function inverse
#include <stdio.h>
int main() {
//code
int mat[10][10], i, j;
printf("Enter your matrix\n");
for (i = 0; i < 2; i++)
for (j = 0; j < 5; j++) {
scanf("%d", &mat[i][j]);
}
printf("\nHere is your matrix:\n");
for (i = 0; i < 2; i++) {
for (j = 0; j < 5; j++) {
if(j==4) //only for 5th column
{
// int temp=mat[i][j]; // can use temporary variable instead of changing actual value matrix (better option)
int remainder, reverse =0;
while(mat[i][j]>0)
{
remainder=mat[i][j]%10;
reverse=reverse*10 + remainder;
mat[i][j]=mat[i][j]/10;
}
mat[i][j]=reverse;
}
printf("%d ", mat[i][j]);
}
printf("\n");
}
return 0;
}
Edited: modified code from the question
#include <stdio.h>
void inverse(int mat1[2][5]) {
int i, j;
for (i = 0; i < 2; i++){
int j=4;
int reversedNumber = 0, remainder=0;
while (mat1[i][j] > 0) {
remainder = mat1[i][j] % 10;
reversedNumber = reversedNumber * 10 + remainder;
mat1[i][j] /= 10;
}
printf("Reversed Number = %d\n",reversedNumber);
}
}
void main()
{
int mat[2][5], i, j;
printf("Enter your matrix\n");
for (i = 0; i < 2; i++)
for (j = 0; j < 5; j++) {
scanf("%d", &mat[i][j]);
}
printf("\nHere is your matrix:\n");
for (i = 0; i < 2; i++) {
for (j = 0; j < 5; j++) {
printf("%d ", mat[i][j]);
}
printf("\n");
}
inverse(mat);
}
hope this helps.
You have to pass the matrix to the inverse function so that the matrix (mat) can be modified. If you declare a separate mat array inside inverse then that's a different scope. You also have to figure out how many digits there are in the number. You can use <math.h> functions, or the example below uses basic calculations.
void inverse(int mat[2][5])
{
for(int i = 0; i < 2; i++)
for(int j = 0; j < 5; j++)
{
int n = mat[i][j];
int digits = 0;
while(n > 0)
{
digits++;
n /= 10;
}
n = mat[i][j];
int rev = 0;
while(digits > 0)
{
int x = n % 10;
for(int c = 0; c < digits - 1; c++)
x *= 10;
rev += x;
n /= 10;
digits--;
}
mat[i][j] = rev;
}
}
int main(void)
{
int mat[2][5] = {
1, 2, 3, 4, 89,
3, 8, 6, 8, 91 };
inverse(mat);
for(int i = 0; i < 2; i++)
{
for(int j = 0; j < 5; j++)
printf("%d ", mat[i][j]);
printf("\n");
}
return 0;
}
I'm trying to print out a hollow, open tent shape using asterisk stars "*". The code uses two for loops, the first for the rows, and the other for the columns.
following is my code:
void printTent(int n)
{
int j = 1;
int i = 1;
if (n == 1) {
printf("*");
} else {
for(i = 0; i < n; i++) {
for(j = 0; j < n; j++) {
printf(" ");
}
if(j == n) {
printf("*");
for(j = 1; j <= n; j++) {
printf(" ");
}
}
}
}
}
int main()
{
printTent(4);
}
Output obtained:
* * * *
Desired output:
*
* *
* *
* *
I don't think you will need that
if (n == 1) {
printf("*");
}
We can take care of that in what you've written in the else part.
For n=4, the number of spaces to be printed at the start of each line is 3, 2, 1 & 0.
You seem to be trying to accomplish that with your first inner loop. But
for(j = 0; j < n; j++) {
printf(" ");
}
will always print n spaces. We need to reduce the number of spaces printed by 1 on each iteration of the outer loop.
Coming to your second loop,
for(j = 1; j <= n; j++) {
printf(" ");
}
This has a similar problem only difference being the incrementation of the number of spaces printed.
Try something like this
void printTentNMMod(int n)
{
int j;
int i;
for(i = 0; i < n; i++) {
for(j = i; j < n; j++) {
printf(" ");
}
printf("*");
if(i!=0)
{
for(j=0; j<2*(i-1)+1; ++j)
{
printf(" ");
}
printf("*");
}
printf("\n");
}
}
Also, you could shorten this to
void printTent(int n)
{
int j;
int i;
for(i = 0; i < n; i++) {
printf("%*c", n-i, '*');
if(i!=0)
{
printf("%*c", 2*i, '*');
}
printf("\n");
}
}
The * in %*c will set the number of places occupied by the character printed by the %c.
I've finished it and I have written annotation.
void printTent(int n)
{
int j = 1;
int i = 1;
if (n == 1) {
printf("*");
}
else {
for (i = 0; i < n; i++) {
for (j = 0; j < n -i; j++) {// you should use n-i instead of n because the number of spaces is decreasing
printf(" ");
}
if (j == n-i) { //
printf("*");
for (j = 1; j <= i * 2 - 1; j++)//this loop outputs spaces between two "*"
{
printf(" ");
}
if (i != 0)//the first line only needs one "*"
printf("*");
printf("\n"); //Line breaks
}
}
}
}
Another way.
#include <stdio.h>
int main() {
int i, j;
int height = 5;
for(i = height; i > 0; i--) {
for(j = 1; j < height * 2; j++) {
if(j == i || j == height * 2 - i)
printf("*");
else
printf(" ");
}
puts("");
}
return 0;
}
Output
*
* *
* *
* *
* *
I am writing a program that arranges an array in nondecreasing order; then, it inserts a value into the sequence. I can easily get numbers in the beginning and the middle of the array, but whenever I add a number that should go at the end, I keep getting 0. Where am I going wrong?
#include <stdio.h>
int main()
{
int array[10];
int i, j, n, m, temp, key, pos;
printf("Enter number of elements:\n");
scanf("%d", &n);
printf("Enter the elements:\n");
for (i = 0; i < n; i++)
{
scanf("%d", &array[i]);
}
printf("Input array elements:\n");
for (i = 0; i < n; i++)
{
printf("%d\n", array[i]);
}
for (i = 0; i < n; i++)
{
for (j = i + 1; j < n; j++)
{
if (array[i] > array[j])
{
temp = array[i];
array[i] = array[j];
array[j] = temp;
}
}
}
printf("Sorted list is\n");
for (i = 0; i < n; i++)
{
printf("%d\n", array[i]);
}
printf("Enter the element to be inserted X:\n");
scanf("%d", &key);
for (i = 0; ; i++)
{
if (key < array[i])
{
pos = i;
break;
}
}
m = n - pos + 1 ;
for (i = 0; i <= m; i++)
{
array[n - i + 2] = array[n - i + 1] ;
}
array[pos] = key;
printf("Final list is:\n");
for (i = 0; i < n + 1; i++)
{
printf("%d\n", array[i]);
}
}
If the number to be entered is larger than all elements the following loop poses an issue.
...
for (i = 0; ; i++)
{
if (key < array[i])
{
pos = i;
break;
}
}
If the number is largest,then the pos will be junk and not n.The default value of an array is junk.
Replace it with this.
for (i = 0;i<n ; i++)
{
if (key < array[i])
{
break;
}
}
pos = i;
...