I was supposed to do this exercise: Write a program in C to print a frequency chart on the screen.
Input and output: The program receives as input a sequence of triples (number, frequency, character). For each sequence it should print a slash, producing a graph as in the example below.
Example For input
(5,12, -) (4,17, -) (2,1, -) (1,19, +)
the program should print
5 | ------------ 12
4 | ----------------- 17
2 | -
1 | +++++++++++++++++++ 19
I realize that if I put a space before the sentence in the scanf function, it works very well, but the program desdon't end when it was expected
int main()
{
int x, b, i, u;
char n;
do{
u = scanf(" (%d,%d,%c)", &x, &b, &n);
printf("%d |", x);
for (i = 0; i < b; i++){
printf("%c", n);
}
printf(" %d\n", b);
}while(u == 3);
}
It was expected that, when the scanf don't read the 3 things it was supposed to, the while loop ends and the program is finished. But, when it happens, he still waiting for a new input. How do I fix that?
just check for the returned value of u and then use an if condition. This shold stop the while loop and exit the program
int main()
{
int x, b, i, u;
char n;
do{
u = scanf(" (%d,%d,%c)", &x, &b, &n);
if(u == 3){
printf("%d |", x);
for (i = 0; i < b; i++){
printf("%c", n);
}
printf(" %d\n", b);
}
}while(u == 3);
Related
Can someone help me. My code is printing an extra number
It's suppose to work like this:
if is N=38
then it's suppose to print
32.0
33.8
35.6
37.4
but mine prints
32.0
33.8
35.6
37.4
39.2
how do i get rid of the last number. I'm still a beginner so i'm quite bad at this
#include<stdio.h>
int main(){
int i, n;
float f;
printf("toogoo oruulna uu: ");
scanf("%d", &n);
i=0;
while (f<=n){
f = (9.0/5.0 * i) + 32;
printf("%.1f\n", f);
i++;
}
return 0;
}
A quick fix
while (1){
f = (9.0/5.0 * i) + 32;
if(f>n) // Move condition to after calculation
break;
printf("%.1f\n", f);
i++;
}
This will also solve the bug that you're using f before it's initialized.
You can do this:
#include<stdio.h>
int main(){
int i, n;
float f;
printf("toogoo oruulna uu: ");
scanf("%d", &n);
i=0;
f=0;
while (f<=(n-1)){
f = (9.0/5.0 * i) + 32;
printf("%.1f\n", f);
i++;
}
return 0;
}
Look while (f<=(n-1)) , the while loop will stop 1 iteration earlier and make sure you are setting the f variable with a value before you use it!
#include <stdio.h>
#include <stdlib.h>
int main() {
int i;
int mult;
int n;
int ans;
ans = mult * i;
printf("Please enter a multiple you want to explore.");
scanf("%d", &mult);
printf("Please enter the number which you would want to multiply this number till.");
scanf("%d", &n);
for(i = 0; i<n; i++) {
printf("%d x %d = %d \n", &mult, &i , &ans);
}
return 0;
}
Hi guys, this is a simple code which is supposed to help the user to list the times table for n times. However, i am receiving undefined behaviour and I am quite stumped as to what is wrong with my implementation of my "for" loop.
I am receiving this as my output.
6356744 x 6356748 = 6356736
for n times in my consoles.
I want to ask
Is anything wrong with the logic of my code? (i assume i do have a problem with my code so please do enlighten me)
Would it be better(or even possible) to use pointers to point to the memory addresses of the mentioned variables when i have to change the value of the variables constantly? If yes, how do i go around doing it?
Thanks!
In printf you must provide integers. You are now giving the addresses of integers. So change
printf("%d x %d = %d \n", &mult, &i , &ans);
to
printf("%d x %d = %d \n", mult, i, ans);
and to make the table, replace ans with just mult*i, so:
printf("%d x %d = %d \n", mult, i, mult*i);
You should also check the return value of scanf to check if it has succeeded reading your input:
do {
printf("Please enter a multiple you want to explore.");
} while (scanf("%d", &mult)!=1);
do {
printf("Please enter the number which you would want to multiply this number till.");
} while (scanf("%d", &n)!=1);
The things you see are the values of the variables memory location.
Change your lines inside for loop as below
ans = mult * i;
printf("%d x %d = %d \n", mult, i, ans);
There are some mistakes in your code .
you are using the & operator in print statement which is used to print the address of the variable.
Initiate the loop with the value '1' instead of '0' & execute the loop till 'i' less than equal to 'n'.
instead of using the ans variable outside the loop , use it inside the loop as it evaluate the multiplication result in each iteration of the loop.
#include <stdio.h>
int main()
{
int i;
int mult;
int n;
int ans;
printf("Please enter a multiple you want to explore.");
scanf("%d", &mult);
printf("Please enter the number which you would want to multiply this number till.");
scanf("%d", &n);
for(i = 1; i<=n; i++) {
ans = mult*i ;
printf("%d x %d = %d \n", mult, i , ans);
}
return 0;
}
My console keeps on crashing after entering a few numbers. I am trying to get an array of 10 numbers from the user thru the console and then taking count of positives, negatives, evens, and odds. What am I doing wrong?
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
int pos, neg, even, odd;
int nums[10];
printf("Give me 10 numbers: ");
pos = neg = even = odd = 0;
for(int i = 0; i < 10; i++){
scanf(" %d", nums[i]);
if(nums[i] > 0){
pos++;
if(nums[i] % 2 == 0){
even++;
}
else{
odd++;
}
}
else{
neg++;
}
}
printf("Positives: %d, Negatives: %d, Evens: %d, Odds: %d\n", pos, neg, even, odd);
return 0;
}
In your code,
scanf(" %d", nums[i]);
should be
scanf(" %d", &(nums[i]));
or,
scanf(" %d", nums+i);
as you need to pass the pointer to variable as the format specifier's argument in scanf() .
To elaborate, %d expects a pointer to int and what you're supplying is an int variable. it invokes undefined behavior.
That said,
Always check the return value of scanf() to ensure proper scanning.
int main() should be int main(void) to conform to the standard.
Modify scanf like scanf(" %d", &nums[i]);
scanf(" %d", nums[i]);
Scanf expects a pointer to a location to write to, and you're not giving it one.
Change your scanf to:
scanf(" %d", &(nums[i]));
to make your program work.
With this change I tested your program with stdin of
20 10 9 1 39 1 2 2 31 1
And recieved output:
Give me 10 numbers: Positives: 10, Negatives: 0, Evens: 4, Odds: 6
ideone of the thing for your testing purposes.
Change scanf(" %d", nums[i]); to scanf(" %d", &nums[i]);, because scanf() needs addresses. The parentheses around nums[i] isn't necessary, and may effect readability.
Also note that 0 is even, but not negative.
When scanf is usedto convert numbers, it expects a pointer to the corresponding type as argument, in your case int *:
scanf(" %d", &nums[i]);
This should get rid of your crash. scanf has a return value, namely the number of conversions made or the special value EOF to indicate the end of input. Please check it, otherwise you can't be sure that you have read a valid number.
When you look at your code, you'll notice that you don't need an array. Afterreading the number, you don't do aything with the array. You just keep a tally of odd, even and so on numbers. That means you just need a single integer to store the current number. That also extends your program nicely to inputs of any length.
Here's a variant that reads numbers until the end of input is reached (by pressing Ctrl-D or Ctrl-Z) or until a non-number is entered, e.g. "stop":
#include <stdlib.h>
#include <stdio.h>
int main()
{
int count = 0;
int pos = 0;
int neg = 0;
int even = 0;
int odd = 0;
int num;
while (scanf("%d", &num) == 1) {
count++;
if (num > 0) pos++;
if (num < 0) neg++;
if (num % 2 == 0) even++;
if (num % 2 != 0) odd++;
}
printf("%d numbers, of which:\n", count);
printf(" %d positive\n", pos);
printf(" %d negative\n", neg);
printf(" %d even\n", even);
printf(" %d odd\n", odd);
return 0;
}
Change scanf statement after for loop to
scanf(" %d", &nums[i]);
I'm trying to get input in an array, I expect input like the following.
5 (Number of the second dimensions in the array)
2 (Number of the first dimensions in the array)
So we get an array deeln[2][5] in this example. I try to get it with the following code:
#include <stdio.h>
#include <string.h>
#include <stdbool.h>
bool isinarray(int val, int *arr, int size){
int countimp;
for (countimp=0; countimp < size; countimp++) {
if (arr[countimp] == val)
return true;
}
return false;
}
int main(void){
int k, d, ci, cj, ck, ta;
//get input
scanf("%i", &k);
scanf("%i", &d);
int deeln[d][k], temp[k];
for(ci = 0; ci < d; ci++){
printf("d= %i, ci= %i \n", d, ci);
scanf("%s", temp);
for(cj = 0; cj < k; cj++){
deeln[ci][cj] = temp[cj*2]-'0';
}
}
//loop while.
}
But i've got a problem, whenever i try to input, the program runs automaticly without getting any input when it loops around the third scanf for the 2nd or 3rd time. So then i'm not able to input anything.
What to do? Has it something to do with pointers or am i using scanf wrong?
UPDATE:
If I enter a printf after printf("cj is nu %i \n", cj); then the output also just came after the loop was going its own way. and not before i should give more input, using the third scanf.
The solution of my question was quite easy. I found it after thinking of my input. The problem was that in the input, as described, there were spaces. Somehow scanf can't handle with spaces, unless you use some other syntax. But my solution is to just use fgets instead of scanf where I wanted to get the input. So the new and working code is as follows:
#include <stdio.h>
#include <string.h>
#include <stdbool.h>
bool isinarray(int val, int *arr, int size){
int countimp = 0;
for (countimp=0; countimp < size; countimp++) {
if (arr[countimp] == val)
return true;
}
return false;
}
int main(void){
int t, k = 0, d = 0, ci = 0, cj = 0, ta = 0;
//get input
scanf("%i", &k);
scanf("%i", &d);
char temp[20];
int deeln[d][k];
memset(deeln, 0 , sizeof(deeln));
memset(temp, 0 , sizeof(temp));
for(ci = 0; ci < d; ci++){
fgets(temp, 20, stdin);
for(cj = 0; cj < k; cj++){
ta = cj*2;
deeln[ci][cj] = temp[ta]-'0';
}
}
//loop while.
return 1;
}
Thanks for helping everbody, even though we all didn't came to this. But I hope it will help others!
Two places to look:
1)
cj = 0;//initialize cj before using here
scanf("%i", &temp[cj]);//temp is both an array, and an int. Fix your format specifier,
//and use an index operator - temp[?] (not sure I am using the right index)
2)
deeln[ci][cj] = temp[cj*2]-'0'; //fix your logic here (array index will be exceeded)
An example of working code...
int main(void){
int k, d, ci, cj, ck, ta;
//get input
scanf("%i", &k);
scanf("%i", &d);
int deeln[d][k], temp[k];
for(ci = 0; ci < d; ci++){
printf("d= %i, ci= %i \n", d, ci);
for(cj = 0; cj < k; cj++){
if(scanf("%i", &temp[cj]) != EOF)
{
deeln[ci][cj] = temp[cj]-'0';
}
else deeln[ci][cj] = -1;
}
}
getchar();
//loop while.
}
you can play with the index of temp[cj] to make it what you actually want, but I assume you are intending to read from stdin, then populate deeln[][] with that value, for each scanf.
If you want to parse a string containing spaces and digets, "1 3 8 5 3", you could use strtok()
But your code as it is is not reading a string in, it is reading integers.
This is not perfect, you will have to do some debug, but will illustrate strtok(). You have to enter spaces between each digit after indices are selected: i.e.:
3
3
4 6 8
2 4 7
1 2 8
int main(void){
int k, d, ci, cj, ck, ta;
//get input
scanf("%i", &k);
scanf("%i", &d);
char inStr[d][k*5]; //space for up to k 3 digit numbers with 1 space each
char *buf=0;
int deeln[d][k], temp[k];
for(ci = 0; ci < d; ci++){
printf("d= %i, ci= %i \n", d, ci);
if(scanf("%s ", inStr[ci]) != EOF)
{
buf = strtok(inStr[ci], " ");
cj = 0;
while(buf && (cj < k))
{
deeln[ci][cj] = atoi(buf);
cj++;
}
}
}
//getchar();waits for user input, pauses execution
}
I have a problem, I tried to write a program to show the whole sum from 1 to 22 and after that, to do 2 while loops. The first one is supposed to perform the sum of some numbers given by the user, as an example: you type 10, 30 and 40 then as you enter a 0 the program sums the first three numbers. Unfortunetly the first while loop is not working. It goes directly to the last while loop where it is supposed to type a decimal numbers like (10.20 30.50 40.55) and after you type 0 again it sum those numbers and add and multipli every entry with 1.19. So far the last loop is working properly, unfortunately the second loop does not, if I move printf and scanf over the while it let me write but just start writing w/o stopping the number I wrote . Thank You in advance!
Here is the code :
#include <stdio.h>
int main()
{
int sum = 0;
int a;
int b;
double i;
double sum1 = 0;
for (a= 0; a <= 22; a++) {
sum = sum + a;
printf("the sum from 1 till 22 : %i\n ", sum);
}
while (b != 0) {
printf("type a number:");
scanf("%i", &b);
sum += b;
printf("%i\n", b);
}
printf("the sum is : %i\n", sum);
while(i !=0) {
printf ("Type a decimal number:");
scanf ("%lf",&i);
sum1 += i*1.19;
printf("%lf\n", i);
}
printf("The decimal summ is: %lf\n",sum1);
return 0;
}
You don't initialise i to any value before entering the loop with
while(i != 0)
i might very well be zero at this point, so your loop won't be entered even once. Initialising i to a non-zero value should fix this particular problem. The same holds for the variable b.
You should turn on warnings in your compiler, so it can show you problems like this one.
The first time the condition of the second while is evaluated, b has undefined value, since it wasn't initialized. The same applies to the third while.
Whether or not both loops are executed is only a question of chance.
Initialize both variables with non-zero values to ensure both whiles are entering. Or use a do-while:
do {
printf("type a number:");
scanf("%i", &b);
sum += b;
printf("%i\n", b);
} while (b != 0);
Don't test b with while, test it after the user enters the number. Then you can use break to exit the loop.
while (1) {
printf("type a number:");
scanf("%i", &b);
if (b == 0) {
break;
}
sum += b;
printf("%i\n", b);
}
while(1) {
printf ("Type a decimal number:");
scanf ("%lf",&i);
if (i == 0.0) {
break;
}
sum1 += i*1.19;
printf("%lf\n", i);
}
Your only issues are initialization: see edits in the code below. (it compiles and runs)
Did you get any compiler warnings for these? If not, you should change your settings so you do.
#include <stdio.h>
int main()
{
int sum = 0;
int a;
int b=-1; //initialize (any non-zero value will work)
double i;
double sum1 = 0;
for (a= 0; a <= 22; a++) {//a initialized in for(...) statement, (this is good)
sum = sum + a;
printf("the sum from 1 till 22 : %i\n ", sum);
}
while (b != 0) { //b Needs to be initialized before using (done above)
printf("type a number:");
scanf("%i", &b);
sum += b;
printf("%i\n", b);
}
printf("the sum is : %i\n", sum);
i=-1; //initialize i to any non-zero value
while(i !=0) {
printf ("Type a decimal number:");
scanf ("%lf",&i);
sum1 += i*1.19;
printf("%lf\n", i);
}
printf("The decimal summ is: %lf\n",sum1);
getchar();
return 0;
}