i have this problem that i'm having troubles to solve.
the user needs to enter 15 numbers (whole numbers) and i need to check if there's a palindrome.
if there are more then one i must take the longest one, and if there are more then one with the same size, i must take the one whose index comes first. i.e:
Input:
1 2 1 3 5 6 7 8 9 4 5 6 8 9 8
Output:
Palindrome Found: 121
Input:
1 2 1 3 3 1 6 4 8 7 9 5 4 8 6
Output:
1 3 3 1
that is my code at the moment:
when i run it, the values of k and array1[k], seems to be an error. i've gor them back with the value 5373952.
even if there is a palindrome it call back that the palindrome was not found.
#include <stdio.h>
#include <stdlib.h>
int main()
{
double arr[15]={0};
int array1[15];
int i,j,k=0;
for (i=0; i<15; i++) // the program is asking for 15 numbers from the user.
{
scanf("%lf", &arr[i]);
if ((arr[i]-(int)arr[i])!= 0)// if the number is not a whole number, the program will stop immediately.
{
printf("Error \n");
return (0);
}
}
for (i=0; i<15; i++)
{
for(j=14; j>=i; j--) // going back-wards to the start. checking at each point for a match.
{
if ((int)arr[i]==(int)arr[j])
{
array1[k]=(int)arr[j];
i++;
j--;
k++;
break;
}
}
}
if ( (int)arr[j] == array1[k] )
{
printf("Palindrome Found:%d \n", array1[k]);
}
else
{
printf("Palindrome Not Found \n");
}
return (0);
}
The number must be between 0 and 9, or can be bigger? For example
1 2 13 22 16 4
Anyway, it's wise to work with the input as a string.
#include <stdio.h>
int main(void){
int arr[15]={0};
int i,j;
int start, end, max_len = 1;
for (i=0; i<15; i++){
if(1 != scanf("%1d", &arr[i]) || arr[i] < 0){
printf("input error\n");
return 1;
}
}
for(i = 0; i < 15 - max_len; ++i){
for(j=i+max_len; j<15; ++j){
if(arr[i]==arr[j]){
int found = 1;
int s, e, len = j - i + 1;
for(s=i, e=j; s < e; ++s, --e){
if(arr[s] != arr[e]){
found = 0;
break;
}
}
if(found && max_len < len){
start = i;
end = j;
max_len = len;
}
}
}
}
if(max_len == 1)
printf("Palindrome Not Found \n");
else {
printf("Palindrome Found:");
for(i=start; i<=end; ++i)
printf(" %d", arr[i]);
printf("\n");
}
return 0;
}
Related
Im trying to make a program that will get sequence from the user that end with 0, and then i want to print the last 5 numbers (not including the 0).
I can assume that the user will input all the numbers in one line and will end it with 0.
I wrote that code but something is wrong with it, I think its something about the scanf line.
Input:
1 6 9 5 2 1 4 3 0
Output: no output
#include <stdio.h>
#define N 5
int main()
{
int arr[N] = {0};
int last_input, j;
printf("please enter more than %d number and than enter 0: \n", N);
last_input = 0;
while (last_input<N) {
scanf(" %d", &j);
if (j == '0') {
last_input = N;
break;
}
else {
arr[last_input] = j;
}
if (last_input==(N-1)) {
last_input=-1;
}
++last_input;
}
printf("The last %d numbers u entered are:\n", N);
for (j=(last_input+1); j<N; ++j) {
printf(" %d", arr[j]);
}
for (j=0; j<last_input; ++j) {
printf(" %d", arr[j]);
}
return 0;
}
This comparison
if (j == '0') {
does not make a sense because the user will try to enter the integer value 0 instead of the value (for example ASCII 30h or EBCDIC F0h) for the character '0'.
You need to write at least
if (j == 0) {
Due to these sub-statements of the if statement
last_input = N;
break;
this for loop
for (j=(last_input+1); j<N; ++j) {
printf(" %d", arr[j]);
}
is never executed and does not make a sense.
This statement
last_input=-1;
results in breaking the order of the N last elements in its output. And moreover the result value of the variable last_input will be incorrect.
You need to move elements of the array one position left. For this purpose you can use a loop of standard C function memmove.
The program can look the following way.
#include <stdio.h>
#include <string.h>
int main( void )
{
enum { N = 5 };
int arr[N];
printf( "Please enter at least not less than %d numbers (0 - stop): ", N );
size_t count = 0;
for (int num; scanf( "%d", &num ) == 1 && num != 0; )
{
if (count != N)
{
arr[count++] = num;
}
else
{
memmove( arr, arr + 1, ( N - 1 ) * sizeof( int ) );
arr[N - 1] = num;
}
}
if (count != 0)
{
printf( "The last %zu numbers u entered are: ", count );
for (size_t i = 0; i < count; i++)
{
printf( "%d ", arr[i] );
}
putchar( '\n' );
}
else
{
puts( "There are no entered numbers." );
}
}
The program output might look like
Please enter at least not less than 5 numbers (0 - stop): 1 2 3 4 5 6 7 8 9 0
The last 5 numbers u entered are: 5 6 7 8 9
I made some changes based on ur comments and now its work fine!
#include <stdio.h>
#define N 5
int main()
{
int arr[N] = {0};
int last_input, j;
printf("please enter more than %d number and than enter 0: \n", N);
last_input = 0;
while (last_input<N) {
scanf("%d", &j);
if (j == 0) {
break;
}
else {
arr[last_input] = j;
}
if (last_input==(N-1)) {
last_input=-1;
}
++last_input;
}
printf("The last %d numbers u entered are:\n", N);
for (j=(last_input); j<N; ++j) {
printf("%d ", arr[j]);
}
for (j=0; j<last_input; ++j) {
printf("%d ", arr[j]);
}
return 0;
}
thank u guys <3.
I have started learning C language. I wrote this program to find all prime numbers between the given range but I am unable to get the expected output.
Can anyone tell me what's wrong with this program please?
#include <stdio.h>
#include <conio.h>
void main() {
int min, max, i, j, count = 0;
printf("Enter Your First Number\n");
scanf("%d", &min);
printf("Enter Your Last Number\n");
scanf("%d", &max);
for(i=min; i<=max; i++) {
for(j=1; j<=i; j++) {
if(i % j == 0) {
count++;
}
}
if(count==2) {
printf("%d\t",i);
}
}
getch();
}
I just suggest getting rid of that count variable.
How do you know if a number N is prime? If for every j in the range (2 to N-1) you have N%j != 0.
So:
In the inner loop, use j from 2 to N-1 (instead of from 1 to N as you used tio do). In fact N%1 and N%N will be 0
The first time you find a j so that N % j == 0 break. You are sure it's not prime
Why incrementing count? For a prime number the j counter will be equal to i (because you looped until j<i, and the last j++ made j
equal to i). So just check for j == i and print the prime number i
#include <stdio.h>
#include <conio.h>
int main( void )
{
int min, max, i, j, count = 0;
printf("Enter Your First Number\n");
scanf("%d", &min);
printf("Enter Your Last Number\n");
scanf("%d", &max);
for(i=min; i<=max; i++)
{
// Was for(j=1; j<=i; j++)
for(j=2; j<i; j++)
{
if(i % j == 0)
{
//Was count++;
break;
}
}
//Was if(count==2)
if(j == i)
{
printf("%d\t",i);
}
}
getch();
return 0;
}
Here you are.
#include <stdio.h>
int main( void )
{
printf( "Enter the range of numbers (two unsigned integer numbers): " );
unsigned int first = 0, last = 0;
scanf( "%u %u", &first, &last );
if ( last < first )
{
unsigned int tmp = first;
first = last;
last = tmp;
}
do
{
int prime = first % 2 == 0 ? first == 2 : first != 1;
for ( unsigned int i = 3; prime && i <= first / i; i += 2 )
{
prime = first % i != 0;
}
if ( prime ) printf( "%u ", first );
} while ( first++ != last );
putchar( '\n' );
return 0;
}
The program output might look like
Enter the range of numbers (two unsigned integer numbers): 0 100
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97
As for your program then you need re-initialize the variable count before the inner loop
for(i=min; i<=max; i++) {
count = 0;
for(j=1; j<=i; j++) {
if(i % j == 0) {
count++;
}
}
And the inner loop is inefficient.
Need to reset the value of count. It starts at count=0, then for any inputs, the loops will count up. The For each outer loop index, it will go like this:
1 (1%1=0 --> count++, count = 1)
2 (2%1=0 --> count++, and 2%2=0 --> count++, count = 3)
3 (3%1=0 --> count++, and 3%3=0 --> count++, count = 5)
etc... until max is reached.
You can use a simple isprime function to check whether a number is prime or not and then call the function for the given interval.
To find whether a number is prime or not , we can use a simple primality test to check it.
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
bool isprime(int n)
{
if(n <= 1) return false;
if(n <= 3) return true;
if(n%2 == 0 || n%3 == 0) return false;
for(int i = 5;i*i <= n;i += 6)
{
if(n%i == 0 || n%(i + 2) == 0)
{
return false;
}
}
return true;
}
int main()
{
int a,b;
printf("Enter the first number :");
scanf("%d",&a);
printf("Enter the second number :");
scanf("%d",&b);
for(int i = a;i <= b;i++)
{
if(isprime(i)) printf("%d ",i);
}
return 0;
}
There is a simple change you should do:
#include <stdio.h>
#include <conio.h>
void main() {
int min, max, i, j, count;
printf("Enter Your First Number\n");
scanf("%d", &min);
printf("Enter Your Last Number\n");
scanf("%d", &max);
for(i=min; i<=max; i++)
{
count=1;
for(j=2; j<=i; j++)
{
if(i % j == 0) {
count++;
}
}
if(count==2) {
printf("%d\t",i);
}
}
}
My answer may be a bit late, but since it's the same issue, i'll write it here in case it helps someone else coming to this thread in the future.
My code is written from the POV of a beginner (No complex functions or data types are used) as this is a code that mostly they will get stuck on.
Working:
User inputs the range.
Using the for loop, each number in the range is sent to the isprime function which returns TRUE or FALSE after checking the condition for being a prime number.
if TRUE : program prints the number.
if FALSE : program skips the number using continue function.
#include<stdio.h>
int isprime(int num);
int main() {
int min, max;
printf("Input the low number: ");
scanf("%d", &min);
printf("Input the high number: ");
scanf("%d", &max);
for(int i = min; i<=max; i++) {
if(isprime(i) == 1) {
printf("%d ", i);
}
else if(isprime(i) == 0){
continue;
}
}
return 0;
}
int isprime(int num) {
int count = 0;
for(int i=2; i<=(num/2); i++) {
if(num % i == 0 ) {
count ++;
}
else{
continue;
}
}
if(count>0){
return 0;
}
else if (count == 0){
return 1;
}
}
I am trying to create a C program that reads standard input until it reaches the end-of-input, then store the even numbers to an array and prints it.
I don't know why my program isn't working as intended. Any help would be appreciated.
#include <stdio.h>
int main(){
int num = getchar();
int list[10000];//array to store even nums
int i = 0;
while(num != EOF){
if(num % 2 == 0){
list[i] = num;//store even nums
i++;
}
num = getchar();
}
for(int j = 0;j < i;j++){
printf("%d ",list[j]);
}
return 0;
}
//example output from terminal
Test 8 (1 1 2 3 5 8 13 21 34) - failed (Incorrect output)
Your program produced these 1 lines of output:
10 10 50 10 10 10 56 10 10 50 10 52 10
Last line of output above was not terminated with a newline('\n') character
The correct 1 lines of output for this test were:
2 8 34
The difference between your output(-) and the correct output(+) is:
- 10 10 50 10 10 10 56 10 10 50 10 52 10
+ 2 8 34
The input for this test was:
1
1
2
3
5
8
13
21
34
If you only get one line of input you don't have to store all numbers, just print them:
#include <stdio.h>
int main(void)
{
int num;
while (scanf("%d", &num) == 1) {
if(num % 2 == 0)
printf("%d ", num);
}
putchar('\n'); // from your output it is clear that
// a newline at the end is expected.
return 0;
}
If you have to handle multiple lines:
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
int main(void)
{
size_t capacity = 0;
int *numbers = NULL;
size_t count = 0;
int input;
while (scanf("%d", &input) == 1) {
if(input % 2 == 0) {
if(count == capacity) {
capacity += 10;
numbers = realloc(numbers, capacity * sizeof(int));
}
numbers[count++] = input;
}
}
for(size_t i = 0; i < count; ++i)
printf("%d ", numbers[i]);
putchar('\n');
free(numbers);
return 0;
}
getchar() reads only one char at a time, you need to use a function that reads a complete input.
scanf("%d", &num);
or better yet fgets and strtol:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define N 10000
int main(void)
{
int list[N];
int num, i = 0;
char buf[32], *ptr;
while ((i < N) && fgets(buf, sizeof buf, stdin)) {
if (buf[0] == '\n') {
break;
}
num = (int)strtol(buf, &ptr, 10);
if (*ptr != '\n') { // not a valid number
continue;
}
if (num % 2 == 0) {
list[i] = num; //store even nums
i++;
}
}
for (int j = 0; j < i; j++) {
printf("%d ", list[j]);
}
printf("\n");
return 0;
}
Given this example :
int arr[3][7] = { {1,0,0,1,1,1,1}, //should output 4
{0,1,1,1,1,0,1}, //should output 4
{0,0,1,1,1,1,1}}; //should output 5
Find the largest sequence containing number 1, and print line index and number of 1.
Do not count total numbers of 1 in each line. Only if they are one after another.
here is my approach :
int main(){
int i,j,c=0,count=0;
int arr[3][7] = { {1,0,0,1,1,1,1}, //output 4
{0,1,1,1,1,0,1}, //output 4
{0,0,1,1,1,1,1}}; // output 5
for(i=0; i<3; i++){
for(j=0; j<7; j++){
if(arr[i][j] == 1){
c++;
} else if( arr[i][j] == 0 && c > count ) {
count = c;
c = 0;
}
}
printf("%d\n", count);
}
return 0;
}
What i want to get as output now is 4,4,5 but i am getting 1,4,5.
SOLUTION thanks to https://stackoverflow.com/users/1228887/twain249
int main(){
int i,j,c=0,count=0;
int arr[3][7] = { {1,1,0,1,1,1,1}, //output 4
{0,1,1,1,1,0,1}, //output 4
{0,0,1,1,1,1,1}}; // output 5
for(i=0; i<3; i++){
for(j=0; j<7; j++){
if(arr[i][j] == 1){
c++;
} else {
count = c;
c = 0;
}
}
if(c > count){
count = c;
}
printf("%d\n", count);
c=0;
}
return 0;
}
You forgot to handle the case where the longest sequence is the end of the list
after the inner j loop add the following
if (c > count) {
count = c;
}
Also you forgot to add a clear after each check.
After the printout add
c = clear = 0;
EDIT: 1 more error. You need to reset c even if the new sequence isn't the longest.
Change the else if into
else if (arr[i][j] == 0) { // If isn't necessary if 0/1 are your only options
{
if (c > count) {
count = c;
}
c = 0;
}
I'm a C newbie and I'm trying to make a matrix 5x4 only with numbers between 0 and 9 where each number needs to be there 2 times (I'm trying to make the memory game). I got this code but I think that this is quite a mess and its not working, so my question is, how can I improve my code or how can I make this matrix in a different way?
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#define MaxC 4
#define MaxL 5
int main(){
int n1=0, n2=0, n3=0, n4=0, n5=0, n6=0, n7=0, n8=0, n9=0, n0=0;
int i=0,j=0,r;
int n[MaxL][MaxC];
srand(time(NULL));
while(i<5){
j=0;
while(j<4){
r=(rand()%10);
if(r==0 && n0<2){
n0++;
j++;
n[i][j]=r;
printf(" %3d ",n[i][j]);
}
if(r==1 && n1<2){
n1++;
j++;
n[i][j]=r;
printf(" %3d ",n[i][j]);
}
if(r==2 && n2<2){
n2++;
j++;
n[i][j]=r;
printf(" %3d ",n[i][j]);
}
if(r==3 && n3<2){
n3++;
j++;
n[i][j]=r;
printf(" %3d ",n[i][j]);
}
if(r==4 && n4<2){
n4++;
j++;
n[i][j]=r;
printf(" %3d ",n[i][j]);
}
if(r==5 && n5<2){
n5++;
j++;
n[i][j]=r;
printf(" %3d ",n[i][j]);
}
if(r==6 && n6<2){
n6++;
j++;
n[i][j]=r;
printf(" %3d ",n[i][j]);
}
if(r==7 && n7<2){
n7++;
j++;
n[i][j]=r;
printf(" %3d ",n[i][j]);
}
if(r==8 && n8<2){
n8++;
j++;
n[i][j]=r;
printf(" %3d ",n[i][j]);
}
if(r==9 && n9<2){
n9++;
j++;
n[i][j]=r;
printf(" %3d ",n[i][j]);
}
}
i++;
}
return 0;
}
Here is a little change to make your program shorter.
I've placed n0, n1, .... into an array indexed by r.
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define MaxC 4
#define MaxL 5
int main()
{
int na[10] = {0};
int n[MaxL][MaxC], i=0;
srand((unsigned)time(NULL));
while(i<MaxL)
{
int j=0;
while(j<MaxC)
{
int r = rand() % 10;
if(na[r]<2)
{
++na[r];
n[i][j] = r;
printf(" %3d ",n[i][j]);
++j;
}
}
++i;
printf("\n");
}
return 0;
}
Example output:
2 6 1 8
4 7 0 2
5 3 7 8
9 1 0 3
5 6 4 9
Your code keeps trying random number until you have had each number twice. That is not the best approach.
Instead you could initialize the matrix with the 20 numbers at fix locations and then do a random shuffle of the matrix.
First off, you've placed j++ in every if statement. It'll look a lot cleaner if you just leave j++ at the end of the loop. Same goes for the print statement.
Second, if you could post what the program is printing out or describe how it's not working, that would help you get an answer to your problem. I don't see what functional issue your code has without trying it myself.
EDIT: See 4386427's answer for further ways to simplify your code.
May I help you? You can simplify your code if you replace ten the nX variables on array. Look at this:
int main(){
int c[10] = {0};
int i=0,j=0,r;
int n[MaxL][MaxC];
srand(time(NULL));
for(i = 0; i < 5; i++) {
for(j = 0; j < 4; j++) {
do {
r=(rand()%10);
} while( c[r] > 2);
++c[r];
n[i][j]=r;
printf(" %3d ",n[i][j]);
}
printf("\n");
}
return 0;
}