*EDITED*
I fixed some issues but i'm still calling it wrong. Somehow when i don't declare with int the GetRand function more than once i get more error messages.
What i want as a final result is to print the array i created and also print the maximum and average of the values of it (only counting every number > -1).
I'm calling the maxavg() function wrong and i'm getting an error message "Error] expected identifier or '(' before '{' token" at the beginning of maxavg which i haven't been able to fix.
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <limits.h>
int GetRand(int min, int max);
int maxavg();
int main ()
{
int a[21][21], i , j, average, maximum;
for (i = 0; i < 21; i++)
{
for ( j = 0; j < 21; j++)
{
a[i][j] = GetRand(0, 100);
printf("%3d" , a[i][j]);
}
a[2][15] = -1;
a[10][6] = -1;
a[13][5] = -1;
a[15][17] = -1;
a[17][17] = -1;
a[19][6] = -1;
printf("\n");
}
average = maxavg();
maximum = maxavg();
printf("average = %d \n maximum = %d", average, maximum);
return 0;
}
// random seed
int GetRand(int min, int max);
int get ()
{
int i, r;
for (i = 0; i < 21; i++)
{
r = GetRand(0, 100);
printf("Your number is %d \n", r);
}
return(0);
}
int GetRand(int min, int max)
{
static int Init = 0;
int rc;
if (Init == 0)
{
srand(time(NULL));
Init = 1;
}
rc = (rand() % (max - min +1) +min);
return (rc);
}
// max and average
int maxavg();
{
int max=INT_MIN, sum=0, count=0, avg, n, m, current;
current = a[i][j];
avg = sum/count;
for(n = 0; n < 21; n++){
for(m =0; m < 21; m++){
if(current > -1){
sum = sum + current;
count = count + 1;
if(current > max){
max = current;
}
}
}
}
return(0);
}
This program will only print the elements of the array a in the for-loop in main. Apart from GetRand, no other function is called, so get and maxavg are never executed, despite being defined. So yes, you should first of all call it from main if you want to see what it does.
There is also a big problem with the logic of your maxavg function though.
Where is the array you're presuming to iterate over? You haven't passed any parameter to maxavg (nor declared and set a local variable). It looks like you're expecting current to contain these array element values, but the reality is you've never set the value of this variable to anything. You should be using the i and j variables as indexes into the array you should add, as in arr[i][j].
A few other notes:
You really should be setting a[2][15], a[10][6] and so on after the loop has finished, not in every single iteration.
You've declared GetRand twice.
maxavg returns an int, yet there is no return statement in your function ("control reaches end of non-void function").
Related
When running this program using pointers and arrays to calculate the grade point average from the user input, it outputs a garbage value. How can I alter the code so that the output is correct?
void Insert_Grades(int *array)
{
int grades[4];
int i;
for (int i = 0; i < 4; i++)
{
printf("Enter grade %d: ", i + 1);
scanf("%d", &grades[i]);
}
array = grades;
}
void Calculate_Avg(int *array)
{
int i;
float avg;
float sum = 0;
for (i = 0; i < 4; i++)
{
sum += *(array + i);
}
avg = sum / 4;
printf( "Grade point average is: %f ", avg);
}
int main()
{
int grades[4];
int i;
printf("Enter the number of grades:\n");
Insert_Grades(grades);
Calculate_Avg(grades);
printf("\n");
return 0;
}
you cant assign arrays.
This operation assigns local pointer array with reference of the local array grades. For the extral world this operation means nothing.
array = grades;
You need to copy values instead.
memcpy(array, grades, sizeof(grades));
or
for (size_t index = 0; index < 4; index++)
array[index] = grades[index];
There are multiple problem in your code:
in function Insert_Grades, value are read into the local array grades. The last instruction array = grades has no effect because it only modifies the argument value, which is just local variable, a pointer to int that now points to the first element of grade array.
This explains why the program outputs garbage because the array grades defined in the main() function is uninitialized and is not modified by Insert_Grades().
You could copy the array grade to the caller array pointed to by array, but it seems much simpler to use the array pointer to read the values directly where they belong.
the variable i is defined multiple times, with nested scopes.
you should test the return value of scanf() to detect invalid or missing input.
Here is a modified version:
#include <stdio.h>
void Insert_Grades(int *array, int count) {
for (int i = 0; i < count; i++) {
printf("Enter grade %d: ", i + 1);
if (scanf("%d", &array[i]) != 1) {
fprintf(stderr, "invalid input\n");
exit(1);
}
}
}
float Calculate_Avg(const int *array, int count) {
float sum = 0;
for (int i = 0; i < count; i++) {
sum += array[i];
}
return sum / count;
}
int main() {
int grades[4];
int count = sizeof(grades) / sizeof(*grades);
float avg;
printf("Enter the grades:\n");
Insert_Grades(grades, count);
avg = Calculate_Avg(grades, count);
printf("Grade point average is: %.3f\n", avg);
return 0;
}
I am new to programing.
I'm doing an exercise witch the user inserts numbers in an array and the program prints the average of those numbers.
But part of the exercise is making the numbers that the user inserts using a function, and thats where i'm struggling.
my code:
#include <stdio.h>
main() {
int n = 10, i, array1[10];
float sum = 0.0, average;
printf("insert 10 numbers\n");
for (i = 0; i < n; ++i) {
printf("insert digit no%d: ", i + 1);
scanf("%d", &array1[i]);
sum += array1[i];
}
average = sum / n;
printf("average = %.2f", average);
return 0;
}
all the help is much apreciated :)
Here's a small program to show you how functions work:
#include "stdio.h"
void foo(int array[], int size)
{
for (int i = 0; i < size; i++)
scanf("%d", &array[i]);
}
size_t bar(int array[], int size)
{
int sum = 0;
for (int i = 0; i < size; i++)
sum += array[i];
return (sum);
}
int main(void)
{
int array[3] = {0};
int sum;
foo(array, 3);
sum = bar(array, 3);
printf("array sum = %d\n", sum);
return (0);
}
foo and bar are two functions, they both have a return type on the left side, a name (foo/bar), some parameters in the parentheses, and their body declaration between braces.
When you call a function from your main, you'll have to call it with its required parameters. In my exemple, both functions need an integer array, and an integer value as parameters. That's why we called it this way from the main: foo(array, 3); and bar(array, 3).
When we call a function, the given parameters are copied into memory so you can work with those params into the function body as if they were variables.
Some functions have a return type different than void. Those functions are able to (and must) return a value of the return type with the return statement. Those values can be used, assigned etc, as you can see with the instruction sum = bar(array, 3);
Even the main is a function !
If you want to move user input and average calculation into separate methods. It should be done something like this.
#include <stdio.h>
/*
* Takes an array and get input for N items specified
*/
void getUserInputForArray(int array[], int N) {
printf("insert %d numbers\n", N);
for (int i = 0; i < N; ++i) {
printf("insert digit no %d: ", i + 1);
scanf("%d", &array[i]);
}
}
/*
* Calculate average for a given array of size N
*/
float getAverage(int array[], int N) {
// Initialize sum to 0
float sum = 0.0f;
// Iterate through array adding values to sum
for (int i = 0; i < N; i++)
sum += array[i];
// Calculate average
return sum / N;
}
int main() {
int n = 10, array1[10];
// Pass array to method, since arrays in C are passed by pointers.
// So Even if you modify it in method it would get reflected in
// main's array1 too
getUserInputForArray(array1, n);
// Calculate Average by delegating average calculation to getAverage(...) method
float average = getAverage(array1, n);
printf("average = %.2f", average);
return 0;
}
This code is designed to find the sum of digits of 100!. I get the correct ouput in ideone but the wrong one in codeblocks. Please help.
#include <stdio.h>
#include <stdlib.h>
#define size_of_number 160
#define question 100
//Function Prototypes
void initialise(int[]);
int sum_of_digits(int[]);
void factorial(int[],int);
int main()
{
int number[size_of_number];
int sum;
initialise(number);
factorial(number, question);
//Getting the sum of the digits of the number
sum = sum_of_digits(number);
printf("The sum of the digits of %d! is %d.\n",question, sum);
return 0;
}
//Initially, the number is 0 so all it's digits are set to zero.
void initialise(int number[])
{
int i;
for(i = 0; i < size_of_number; i++)
{
number[i] = 0;
}
}
//Finding the factorial by multiplying the digits
void factorial(int number[], int num)
{
int i, first_digit;
int carry, replace, product;
first_digit = 0;
number[first_digit] = 1;
while(num != 1)
{
carry = 0;
for(i = 0; i <= first_digit; i++)
{
product = num*number[i] + carry;
replace = product%10;
carry = product/10;
number[i] = replace;
if( (i == first_digit) && (carry > 0) )
{
first_digit++;
}
}
num--;
}
}
//Finding the sum of all digits
int sum_of_digits(int number[])
{
int i, sum;
for(i = 0; i < size_of_number; i++)
{
sum = sum + number[i];
}
return sum;
}
I had problems with some other programs too. Why s Codeblocks not giving the correct output which is 648 ?
You don't initialize sum in the function sum_of_digits. Normal local variables don't automatically get a starting value in C, so your program has what the C standard calls undefined behaviour. Anything can happen, but what typically does happen is that the variable starts with whatever data happened to be in the place in memory where the variable happened to be located.
I am working on a program that will accept user input to fill an array and then quit when the user enters q. Next the array is passed to a function that finds the largest value in the array. My program seems like it would work, but I believe that user input for the array is incorrect and I am not sure how to solve it.
#include <stdio.h>
#define SIZE 30
int maxnum(int userarray[], int maxx);
int main()
{
int i;
int nums[SIZE];
int largest;
printf("Type integer numbers (up to 30), followed by q to quit:\n");
while(scanf("%d", &nums[i]) == 1)
{
for(i = 0; i < SIZE; i++)
{
//blank
}
}
largest = maxnum(nums, SIZE);
printf("The largest number is: %d\n", largest);
return 0;
}
int maxnum(int userarray[], int maxx)
{
int i;
int maxnumber;
maxnumber = userarray[0];
for(i = 1; i < maxx; i++)
{
if(maxnumber < userarray[i])
{
maxnumber = userarray[i];
}
}
return maxnumber;
}
First i is unitialized.
Then your inner for loop is strange (why someone would do that??) and sets i to SIZE in the end, which is not good.
I don't give more details, but the value of i is trash all the time because of those 2 mistakes it should be:
int i = 0;
while((i<SIZE) && (scanf("%d", &nums[i]) == 1))
{
i++;
}
so you read one by one, and protect against array out of bounds by the second condition.
After that you're passing NUMS
largest = maxnum(nums, SIZE);
whereas the array could contain fewer valid values. Just pass
largest = maxnum(nums, i);
Here is another solution for your problem.
In main() function
int n,i=0;
while(scanf("%d",&n) == 1){
nums[i++] = n;
}
n = maxnum(nums, i);
printf("The largest number is: %d\n", n);
Note : Initialize the value of i=0, Then input and update nums[] array
In maxnum() function
for(i = 0; i < maxx; i++) {
if(maxnumber < userarray[i]){
maxnumber = userarray[i];
}
}
Note: Start i=0 and find the max mumber and return the value
Earlier I posted a question about the coin vending machine problem (the minimum number of coins required). Turns out the issue was a typo in a for loop, so now the program works. The original question was this:
As the programmer of a vending machine controller your are required to compute the minimum number of coins that make up the required change to give back to customers. An efficient solution to this problem takes a dynamic programming approach, starting off computing the number of coins required for a 1 cent change, then for 2 cents, then for 3 cents, until reaching the required change and each time making use of the prior computed number of coins. Write a program containing the function ComputeChange(), that takes a list of valid coins and the required change. This program should repeatedly ask for the required change from the console and call ComputeChange() accordingly. It should also make use of “caching”, where any previously computed intermediate values are retained for subsequent look-up.
The issue is that the code makes use of recursion, so it takes quite a long time to evaluate large values. Making use of caching should improve the issue, but I have no idea how to go about it. The code can be found below.
#include <stdio.h>
#include <limits.h>
int computeChange(int[],int,int);
int min(int[],int);
int main(){
int cur[]={1,2,5,10,20,50,100,200};
int n = sizeof(cur)/sizeof(int);
int v;
printf("Enter a value in euro cents: ");
scanf("%d", &v);
printf("The minimum number of euro coins required is %d", computeChange(cur, v, n));
return 0;
}
int computeChange(int cur[], int v, int n){
if(v < 0)
return INT_MAX;
else if(v == 0)
return 0;
else{
int possible_mins[n], i;
for(i = 0; i < n; i++){
possible_mins[i]=computeChange(cur, v-cur[i], n);
}
return 1+min(possible_mins, n);
};
}
int min(int a[], int n){
int min = INT_MAX, i;
for(i = 0; i < n; i++){
if((a[i]>=0) && (a[i]< min))
min = a[i];
}
return min;
}
With your existing code:
#include <stdio.h>
#include <limits.h>
int computeChange(int[],int,int);
int min(int[],int);
void initChange ();
int change [MAX]; //used for memoization
int main(){
int cur[]={1,2,5,10,20,50,100,200};
int n = sizeof(cur)/sizeof(int);
int v;
initChange ();
printf("Enter a value in euro cents: ");
scanf("%d", &v);
printf("The minimum number of euro coins required is %d", computeChange(cur, v, n));
return 0;
}
void initChange () {
int i =0;
for (i = 0; i < MAX; i++) {
change[i] = INT_MAX;
}
}
int computeChange(int cur[], int v, int n){
if(v < 0)
return INT_MAX;
else if(v == 0)
return 0;
else{
if (change[v] == INT_MAX) {
int possible_mins[n], i;
for(i = 0; i < n; i++){
possible_mins[i]=computeChange(cur, v-cur[i], n);
}
change[v] = 1 + min(possible_mins, n); // memoization
}
return change[v];//you return the memoized value
};
}
int min(int a[], int n){
int min = INT_MAX, i;
for(i = 0; i < n; i++){
if((a[i]>=0) && (a[i]< min))
min = a[i];
}
return min;
}
I already posted a solution using loops in your previous question. I will post it again here:
So the below is the code snippet for your problem using memoization and dynamic programming. The complexity is O(Val*numTypesofCoins).
In the end, change[val] will give you the min number of coins for val.
int main (void) {
int change [MAX];
int cur[]={1,2,5,10,20,50,100,200};
int n = sizeof(a)/sizeof(int);
int val; //whatever user enters to get the num of coins required.
printf("Enter a value in euro cents: ");
scanf("%d", &val);
for (i=0; i <= val; i++) {
change[i] = INT_MAX;
}
for (i=0; i < n; i++) { // change for the currency coins should be 1.
change[cur[i]] = 1;
}
for (i=1; i <= val; i++) {
int min = INT_MAX;
int coins = 0;
if (change[i] != INT_MAX) { // Already got in 2nd loop
continue;
}
for (j=0; j < n; j++) {
if (cur[j] > i) { // coin value greater than i, so break.
break;
}
coins = 1 + change[i - cur[j]];
if (coins < min) {
min = coins;
}
}
change[i] = min;
}
}