i cannot print the values stored in the array someone can see the mistake?
Code:
#include<stdio.h> #include<math.h> #include<time.h> #include<stdlib.h> double randf(); int main() { double s; s=randf(); printf("%lf", s); return 0; } double randf() { double a = 1; double b = 0; double x[8]; for (int i = 0; i <= 8; ++i) { srand((unsigned)time(NULL)); x[i] = rand()*(a - b) / (double)RAND_MAX + b; } return x[i]; }
At what point in your code does the 'for' loop end, and what is 'i' at that point?
now i put the return i inside the loop and it returned me only one value
You should call srand only once, typically near the start of the main function.
You probably should declare the array in main, then pass a pointer to its first element as an argument to randf (e.g., by passing the array as an argument). After that, use a loop to print the elements of the array in main (or in another function designated for that task).
Look up a C++ Reference and learn How To Ask Questions The Smart WayOriginally Posted by Bjarne Stroustrup (2000-10-14)
I did what you told me and i still have some error that do not let me run the code.
Code:#include<stdio.h> #include<time.h> #include<stdlib.h> double randf(double *p); #define SIZE 8 int main() { double arr[SIZE]; randf(&arr[SIZE]); } double randf(double *p) { double a = 1; double b = 0; for (int i = 0; i <= 8; ++i) { srand((unsigned)time(NULL)); *(p + i) = rand()*(a - b) / (double)RAND_MAX + b; } return 0; }
If there is an error, then you should tell us what exactly is the error. Saying the vague "some error" is begging for a vague response like "there are things that you need to fix".
This is wrong:
You're passing a pointer to the element one past the end of the array. Rather, you want to pass a pointer to the first element of the array, so it should be:Code:randf(&arr[SIZE]);
or equivalently because an array is converted to a pointer to its first element in this context:Code:randf(&arr[SIZE]);
I told you that the srand call should be placed near the start of the main function, yet you placed it in the randf function.Code:randf(arr);
In randf, this is wrong:
You did well by defining the named constant SIZE, so you should use it:Code:i <= 8
Note the < instead of <= because you start counting from 0.Code:i < SIZE
Instead of writing *(p + i) write p[i].
Look up a C++ Reference and learn How To Ask Questions The Smart Way
I did it and it workd perfectly, i add two more functions, one calculate the average value of the array and the other reverse this array, the problem is that the program does not print the reverse matrix.
Code:#include<stdio.h> #include<time.h> #include<stdlib.h> double randf(double *p); double average(double *k); double reverse(double *j); #define SIZE 8 int main() { double b; srand((unsigned)time(NULL)); double arr[SIZE]; randf(arr); b = average(arr); printf(" average is equal to %lf\n", b); printf("this is the reverse matrix\n"); reverse(arr); } double randf(double *p) { double a = 1; double b = 0; for (int i = 0; i < SIZE; ++i) { p[i] = rand()*(a - b) / (double)RAND_MAX + b; printf("%lf\n", p[i]); } return 0; } double average(double *k) { double x = 0; for (int i = 0; i < SIZE; ++i) x +=(k[i])/SIZE; return x; } double reverse(double *j) { for (int i = SIZE; i < 0; --i) { j[i] = rand()*(1 - 0) / (double)RAND_MAX + 0; printf("%lf\n", j[i]); } return 0; }
What is the "reverse matrix"? If you want to reverse the elements of the array, then you should be modifying the existing array element values (or a copy thereof), not calling rand() as if you are populating the array all over again.
Look up a C++ Reference and learn How To Ask Questions The Smart Way
