I have to multiply digits by taking input from the user and when he enter 'n' it will produce the answer.
For example (2*3*2 = 12). But I manage to write the code for taking two inputs but can't find the way to take multiple inputs from user and produce the total answer. Here is the code;
void main (void)
{
float f1,f2;
float total;
int status1,status2;
printf("Enter first number to multiply:'n' to quit.\n ");
status1=scanf("%f",&f1);
printf("Enter another number to be multiply:'n' to quit.\n ");
status2=scanf("%f",&f2);
while (status1==1 && status2==1)
{
total=f1*f2;
status1=scanf("%1.0f",&f1);
status2=scanf("%1.0f",&f2);
}
printf("Multiplition Total = %1.0f",total);
getch();
}
You can use a while loop, as follows.
float prod = 1, f;
printf( "Enter the numbers, n to stop.\n" );
while( scanf( "%f", &f ) )
prod *= f;
printf( "product = %f\n", prod );
Tested:
#include <stdio.h>
int main()
{
int total = 1, factor = 1, success;
do
{
total *= factor;
printf("Enter integer number to multiply or 'n' to quit: ");
success = scanf("%d", &factor);
}
while (success);
printf("Multiplication Total = %d\n", total);
return 0;
}
And a piece of advice as you said you start your adventure with C:
Unless you have some specific reason to do otherwise, use double, not float.
However, in your question you asked for digits (integer) multiplication, so int is sufficient. If you can avoid floating point numbers, avoid them. They're much more complicated then integers and can let you in worse problems if you don't use them with caution.
You can refer to What Every Computer Scientist Should Know About Floating-Point Arithmetic.
This would do what you need and handles, 0, 1 or an unlimited number of inputs:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
float f1;
float total = 0;
printf("Enter number: ");
if (scanf("%f",&total))
{
for (;;)
{
printf("Enter number: ");
if (!scanf("%f", &f1))
{
break;
}
total *= f1;
}
}
printf("Multiplication Total = %f\n",total);
getch();
return 0;
}
It keeps a running total as values are entered but it stops on first invalid input, not just when n is entered.
Untested:
float f, p = 1;
printf ("Enter a number: ");
fflush (stdout);
while (scanf("%f", &f) != EOF)
{
p *= f;
printf ("Enter another number: ");
fflush (stdout);
}
printf ("Product: %f\n", p);
Related
For my homework, I am trying to code a calculator which can also calculate average of taken numbers. I don't want to ask for number of numbers because our teacher don't want it in that way. So I thought of scanning values until the user presses "p". But as you would guess, the numbers are float and "p" is a character. What I want to do is assigning the value scanned to both of them if it is possible. I tried different ways, played with the codes but it isn't working properly. So I am seeking your advice.
It prints a value when p is inputted as like 3rd, 5th, 7th (oddth) number (sometimes right, sometimes wrong but I can fix it if I figure this out). But it doesn't print a value in other occasions and expects infinite inputs from the user.
This is the code I have written for this. scanf("%f %c", &number1, &pause); command is where I want to know about, actually.
#include<stdio.h>
float number1, number2, i, result;
char pause;
int main() {
scanf("%f", &number1);
i = 0;
while (pause != 'p') {
number2 = number1 + number2;
scanf("%f %c", &number1, &pause);
i++;
}
result = number2 / (i - 1);
printf("%f", result);
}
Use double not floats if there is no specific reason to do so (like using uC without double FPU).
You do not initialize the variables
Always check the result of the I/O operation.
#include <stdio.h>
int main ()
{
double number1= 0, number2 = 0, i = 0, result = 0;
char pause = 0;
char line[128];
while (pause != 'p')
{
if(fgets(line, sizeof(line), stdin))
{
if(sscanf(line, "%lf %c",&number1, &pause) != 2)
{
printf("Wrong input - try again\n");
pause = 0;
continue;
}
number2 = number1 + number2;
i++;
}
else
{
// do something with I/O error
}
}
result = number2 / (i-1);
printf("%lf",result);
}
You can play with it yourself : https://onlinegdb.com/Hy3y94-3r
I noticed 3 problems with your code.
First I would advise you to use meaningful variables names. number1, number2, etc. and the i which represents the number of inputs given can be an int instead of a float.
Secondly, you lack of printing to the user what's going on in your program; it's better to have messages like "enter your number, do you wanna stop? the result is...etc".
Lastly, having two inputs in one line of code can make it hard to debug, knowing that reading strings and characters in C is already hard for beginners. For example, %c does not skip whitespace before converting a character and can get newline character from the previous data entry.
Here is my fix: I changed some variables' names, printed some messages and read the two inputs in two different lines with adding scanf(" %c") with the space to avoid that problem.
#include<stdio.h>
float sum, temp, result;
int nb;
char pause;
int main () {
pause='a';
while (pause != 'p'){
printf("Enter your number: ");
scanf("%f",&temp);
sum+=temp;
nb++;
printf("type 'p' if you want to stop: ");
scanf(" %c",&pause);
}
result = sum / nb;
printf("the average is : %f",result);
}
I tested it, should work fine
Edit: after explaining that you don't want to ask the user each time, here is how the code should work (the case that the user don't input a float is not treated, and just take it as zero
#include<stdio.h>
#include<string.h>
#include <stdlib.h>
float sum, temp, result;
int nb;
char input[50];
int main () {
sum=0;
nb=0;
printf("Enter your numbers, then type 'p' to stop\n");
do{
printf("Enter your next number: ");
scanf("%s", input);
if(strcmp(input,"p")!=0)
{
float temp= atof(input);
sum+=temp;
nb++;
}
}while(strcmp(input,"p")!=0);
if(nb!=0)
result = sum / nb;
printf("\nThe average is : %f",result);
}
So, I have to write a program to ask the user for an integer, and then that integer will determine how many more entries the user gets before adding all the numbers that were entered. So, if the first entered integer is "5", then the user can enter 5 more integers. Those 5 integers are then added together at the end and displayed. I have written a program with for loops, but for some reason, it is only adding first 4 integers and not the 5th one. Here is the code:
int main() { //declare main function
int c=0,n,i; //declare integers
int sum=0;
printf("\nEnter an integer: "); //ask user for input and create a label
scanf("%d",&n);
if (n>=0) { //use if statement
for (i=0;i<n;i++) //use for loop inside if statement to account for negative integers
{
sum+=c;
printf("Enter an integer: ");
scanf("%d",&c);
}
}
else {
printf("Wrong number. You can only enter positive integers!");
}
printf("The sum of the %d numbers entered is: %d",i,sum);
return 0;
}
Just change the position of
sum+=c;
to after the scanf it should work.
It is good to split the program. use functions. Not everything in the main function.
int getInteger(void)
{
char str[100];
int number;
while(!fgets(str, 100, stdin) || sscanf(str, "%d", &number) != 1)
{
printf("Wrong input. Try again:") ;
}
return number;
}
int main()
{
int nsamples;
long long sum = 0;
printf("Enter number of samples:");
while((nsamples = getInteger()) <= 0)
{
printf("Try again, entered number must be >= 0\n");
}
printf("Enter numbers:\n");
for(int i = 1; i <= nsamples; i++)
{
printf("Sample no %d:", i);
sum += getInteger();
}
printf("The sim is: %lld\n", sum);
}
I have asked for the user to enter in several values to calculate an average, however I'd like to also calculate a gradient which uses the inputted values. How do I name these values so I can use them again? Thank you.
Here is what I have thus far:
#include <stdio.h>
int main () {
int n, i;
float num[1000], total=0, mean;
printf("Enter the amount of x-values:");
scanf("%d", &n);
while (n <= 0 || n > 1000) {
printf("Print error. The number should in range of 0 to 1000.\n");
printf("Please try to enter the amount again: ");
scanf("%d", &n);
}
for (i = 0; i < n; ++i) {
printf("%d. Input x-value:", i+1);
scanf("%f", &num[i]);
total += num[i];
}
mean=total/n;
printf("The mean of all the x-values entered is %.2f to 2 decimal places", mean);
{
float num[1000], total=0, mean;
printf("Enter the amount of y-values:");
scanf("%d", &n);
while (n <= 0 || n > 1000) {
printf("Print error. The number should in range of 0 to 1000.\n");
printf("Please try to enter the amount again: ");
scanf("%d",&n);
}
for (i = 0; i < n; ++i) {
printf("%d. Input y-value:", i+1);
scanf("%f", &num[i]);
total += num[i];
}
mean = total / n;
printf("The mean of all the y-values entered is %.2f to 2 decimal places", mean);
return 0;
}
}
Naming the variable is really up to you, but `int gradient[NUM_ELEMENTS]; seems appropriate. It is an array, which also seems appropriate if it's purpose is to assist in finding the gradient from a series of numbers.
Steps could be:
1) use printf to ask user for values, specify spaces or commas between values. You can also specify a limit of values. Example printf("enter 5 numbers separated by commas\n:");
2) use scanf or similar to read values from standard input (the terminal) into the array: scanf("%d,%d,%d,%d,%d", &gradient[0], &gradient[1], &gradient[2], &gradient[3], &gradient[4]);
3) use the array an a function that will compute the gradient.
Simple example:
(where gradient computation, error checking, bounds checking etc. is all left to you)
int get_gradient(int a[5]);
int main(void) {
int gradient[5];
int iGradient=0;
printf("enter 5 numbers separated by commas");
scanf("%d,%d,%d,%d,%d", &gradient[0], &gradient[1], &gradient[2], &gradient[3], &gradient[4]);
iGradient = get_gradient(gradient);
return 0;
}
int get_gradient(int a[5])
{
return [do computation here using array a];
}
Edit:
The above example works only if you know the number of elements at compile time. It uses an int array that has been created on the stack. If you do not know how big of an array you will need until run-time, for example if user input determines the size, then the array size needs to be determined at run-time. One options is to create the variable needed on the heap. (read about stack and heap here) The following uses some techniques different from the simpler version above to get user input, including a function I called get_int(), which uses scanf() in conjunction with strtol(). Here's the example:
int main(void) {
char input[80]={0};
char **dummy={0};
long *gradient = {0};
int iGradient=0;
int arraysize;
int i;
char* fmt = "%[^\n]%*c";
printf("how many numbers will be entered?");
scanf(fmt, input);
arraysize = strtol(input, dummy, 10);
gradient = calloc(arraysize, sizeof(long));
if(gradient)
{
for(i=0;i<arraysize;i++)
{
gradient[i] = get_int();
}
iGradient = get_gradient(gradient, arraysize);
//free gradient when done getting result
free(gradient);
}
return 0;
}
int get_gradient(int *a, int num)
{
int grad = 0, i;
//do something here to compute gradient
return grad;
}
long get_int(void)
{
char input[80]={0};
char **dummy={0};
char* fmt = "%[^\n]%*c";
printf("Enter integer number and hit return:\n");
scanf(fmt, input);
return strtol(input, dummy, 10);
}
My friend and I are trying to build a program together, but it just doesn't seem to be working. Neither of us have much experience with C, so we just can't spot the issue... Any advice or help would be much appreciated!
Apologies for the slightly awkward lyrics?
[Edit] The problem is that when we input values, we get ridiculous figures like 4586368.
#include "stdafx.h"
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <math.h>
void main()
{
int room[20] = {};
int i;
int rooms = 0;
char option = 0;
int lights = 0;
int hrsUsed = 0;
int Telly = 0;
int TVWatt =0;
int sumTV;
int TVuse = 0;
int Computer = 0;
int compWatt = 0;
int compUsed = 0;
int compTotal;
int kwH_lights;
int fridge = 0;
int washLoad = 0;
int dryerLoad = 0, dishLoad = 0, cookLoad = 0;
int showeruse = 0;
int total_kWh;
printf("Enter number of rooms");
scanf_s("%d", &rooms);
for(i=0;i<rooms;i++)
{
printf("input average wattage of lights");
scanf_s("%d", &lights);
lights=lights/1000;
printf("input number of hours use/day (average)");
scanf_s("%d", &hrsUsed);
kwH_lights=((lights*hrsUsed)*365);
printf("input number of TVs");
scanf_s("%d", &Telly);
printf("input average wattage");
scanf_s("%d", &TVWatt);
printf("input average use a day");
scanf_s("%d", &TVuse);
sumTV=((Telly*(TVWatt/1000))*TVuse)*365;
}
printf("Input number of fridge/freezer");
scanf_s("%d",&fridge);
fridge=(fridge*2)*365;
printf("input number of Computers and/or video game consoles in the house");
scanf_s("%d", &Computer);
for(i=0;i<Computer;i++) {
printf("input wattage");
scanf_s("%d", &compWatt);
printf("input average hrs used/day");
scanf_s("%d", &compUsed);
compTotal=((compWatt/1000)*compUsed)*365;
}
printf("Input average number of washing machine loads /day");
scanf_s("%d",&washLoad);
washLoad=washLoad*365;
printf("Input average number of clothes dryer loads/day");
scanf_s("%d",&dryerLoad);
dryerLoad=(dryerLoad*3)*365;
printf("Input average number of dishwasher loads/day");
scanf_s("%d",&dishLoad);
dishLoad=(dishLoad*1.5)*365;
printf("Input average cooking load/day");
scanf_s("%d",&cookLoad);
cookLoad=(cookLoad*7)*365;
printf("Input average hrs/day of shower usage");
scanf_s("%d",&showeruse);
showeruse=(showeruse*7)*365;
total_kWh=((kwH_lights)+(sumTV)+(fridge)+(compTotal)+(dryerLoad)+(dishLoad)+(cookLoad)+(showeruse));
printf("Total= %d", &total_kWh);
}
You should change this:
printf("Total= %d", &total_kWh);
to that:
printf("Total= %d", total_kWh);
Same is true for all your other integer variables.
There were quite a few mistakes in your code:
you printed the memory-address instead of result value (don't use & with printf if your variable is a plain int)
the computer for-loop had no curly brackets (so only the printf statement was looped)
results were not summed up (in all loops you've just overwritten your inputs from the last loop)
the rooms[] Array was never used - a few other variables also (possible error source, if you wanted to use them and just forgot it)
the result from a multiplication with 1.5 will hold a double value - you should cast that back to int (dishLoad)
The bold mistake is probably that one, why your values were wrong...
Also notice: The 'average number of washing machine loads/clothes dryer loads/ dishwasher loads' should better be asked by week or month... Or should hold Floating Point values: Because everyone I know don't use the washing machine and clothes dryer every day multiple times. So now you can't enter something like once a week (which would be an factor of 0.14, but is not enterable cause all values are stored as int).
Here Comes the code with everything fixed, I could found:
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <math.h>
int main(int argc, char** argv){
int i = 0;
int rooms = 0;
int lights = 0;
int hrsUsed = 0;
int Telly = 0;
int TVWatt =0;
int sumTV = 0;
int TVuse = 0;
int Computer = 0;
int compWatt = 0;
int compUsed = 0;
int compTotal= 0;
int kwH_lights = 0;
int fridge = 0;
int washLoad = 0;
int dryerLoad = 0, dishLoad = 0, cookLoad = 0;
int showeruse = 0;
int total_kWh = 0;
printf("Enter number of rooms: ");
scanf_s("%d", &rooms);
for(i=0;i<rooms;i++){
printf("A few questions about room %d\n", i+1);
printf("input average wattage of lights: ");
scanf_s("%d", &lights);
lights+=lights/1000;
printf("input number of hours use/day (average): ");
scanf_s("%d", &hrsUsed);
kwH_lights+=((lights*hrsUsed)*365);
printf("input number of TVs: ");
scanf_s("%d", &Telly);
printf("input average wattage: ");
scanf_s("%d", &TVWatt);
printf("input average use a day: ");
scanf_s("%d", &TVuse);
sumTV+=((Telly*(TVWatt/1000))*TVuse)*365;
}
printf("Input number of fridge/freezer: ");
scanf_s("%d",&fridge);
fridge=(fridge*2)*365;
printf("input number of Computers and/or video game consoles in the house: ");
scanf_s("%d", &Computer);
for(i=0;i<Computer;i++){
printf("A few questions about computer %d\n", i+1);
printf("input wattage: ");
scanf_s("%d", &compWatt);
printf("input average hrs used/day: ");
scanf_s("%d", &compUsed);
compTotal += ((compWatt/1000)*compUsed)*365;
}
printf("Input average number of washing machine loads/day: ");
scanf_s("%d",&washLoad);
washLoad=washLoad*365;
printf("Input average number of clothes dryer loads/day: ");
scanf_s("%d",&dryerLoad);
dryerLoad=(dryerLoad*3)*365;
printf("Input average number of dishwasher loads/day: ");
scanf_s("%d",&dishLoad);
dishLoad=(int)((dishLoad*1.5)*365);
printf("Input average cooking load/day: ");
scanf_s("%d",&cookLoad);
cookLoad=(cookLoad*7)*365;
printf("Input average hrs/day of shower usage: ");
scanf_s("%d",&showeruse);
showeruse=(showeruse*7)*365;
total_kWh=((kwH_lights)+(sumTV)+(fridge)+(compTotal)+(dryerLoad)+(dishLoad)+(cookLoad)+(showeruse));
printf("Total= %d\n", total_kWh);
system("Pause");
return 0;
}
I hope it helps you out - if you got any questions left, feel free to ask.
My first step would be to correct the second for loop { } ... fix this and ask again.
[EDIT]
your calculations with usages of int values divided by other ints (compwatt / 1000) ... are you sure your idea of using int is correct?
or:
cookLoad=(cookLoad*7)*365;
why multiplying with 7 AND 365? should not the average / day be multiplied by 365 only?
For more readability of your code, you can employ compound assignment operators as below,
Operator Name Syntax Meaning
-------------------------------------------------
Addition assignment a += b a = a + b
Subtraction assignment a -= b a = a - b
Multiplication assignment a *= b a = a * b
Division assignment a /= b a = a / b
I am very new to C. I am using A modern Approach to C programming by King 2nd Edition.
I am stuck on chapter 6. Question 1: Write a program that finds the largest in a series of numbers entered by the user. The program must prompt the user to enter the numbers one by one. When the user enters 0 or a negative number, the program must display the largest non negative number entered.
So far I have:
#include <stdio.h>
int main(void)
{
float a, max, b;
for (a == max; a != 0; a++) {
printf("Enter number:");
scanf("%f", &a);
}
printf("Largest non negative number: %f", max);
return 0;
}
I do not understand the last part of the question, which is how to see which non-negative number is the greatest at the end of user input of the loop.
max = a > a ???
Thanks for your help!
So you want to update max if a is greater than it each iteration thru the loop, like so:
#include <stdio.h>
int main(void)
{
float max = 0, a;
do{
printf("Enter number:");
/* the space in front of the %f causes scanf to skip
* any whitespace. We check the return value to see
* whether something was *actually* read before we
* continue.
*/
if(scanf(" %f", &a) == 1) {
if(a > max){
max = a;
}
}
/* We could have combined the two if's above like this */
/* if((scanf(" %f", &a) == 1) && (a > max)) {
* max = a;
* }
*/
}
while(a > 0);
printf("Largest non negative number: %f", max);
return 0;
}
Then you simply print max at the end.
A do while loop is a better choice here because it needs to run at least once.
#include<stdio.h>
int main()
{
float enter_num,proc=0;
for(;;)
{
printf("Enter the number:");
scanf("%f",&enter_num);
if(enter_num == 0)
{
break;
}
if(enter_num < 0)
{
proc>enter_num;
proc=enter_num;
}
if(proc < enter_num)
{
proc = enter_num;
}
}
printf("Largest number from the above is:%.1f",proc);
return 0;
}