Read file, write to array, find min and max

dr eu

//This program read file *.txt, than 100 float numbers(or int numbers, if they are present) //write in a float array.Next, finds MIN and MAX element in float array with using pointers, //write results on the screan and if there is no more numbers, go to end, else repet all again. #include #include #include #define MAXELEMENTS 100 // MAX numbers of elements //funkcion for max element in float array float *biggest(float table[],int number) { int counter, counter_max; float aretheysame=0; for(counter=0; counter < number; counter++) { if (*(table+counter) > aretheysame) { aretheysame = *(table+counter); counter_max = counter; } } return(&*(table+counter_max)); } //finkcion for min element in float array float *smallest(float table[],int number) { int counter, counter_max=0; float aretheysame=table[0]; for(counter=0; counter < number; counter++) { if (*(table+counter) < aretheysame) { aretheysame = *(table+counter); counter_max = counter; } } return(&*(table+counter_max)); } main(void) { FILE *in; char inter[255]; int num_elements=0; float element; static float table[MAXELEMENTS]; float *small,*big; printf("Adress and value of max and min element in array\n"); printf("Enter file name : "); gets(inter); in= fopen(inter,"r"); if(in == NULL) { printf("Error. No file with this name\n"); exit(1); } while (fscanf(in,"%f",&element) != EOF) { table[num_elements] = element; num_elements++; } if (num_elements > 1) { big=biggest(table,num_elements); printf("\nThe adress of max element is %d",&*big); printf(", with value %f",*big); small=smallest(table,num_elements); printf("\nThe adress of min element is %d",&*small); printf(", with value %f",*small); } else { ; } fclose (in); getchar(); } And *.txt file: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 2000 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75

David Crow

If there are more than 100 numbers in the file, you'll need to change the value of MAXELEMENTS. A better solution would be to use a dynamic array. That way you do not have to keep changing and compiling code when the size of the input file changes.

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

dr eu

How must i do that?

rocky_pulley

I'm having trouble trying to understand what your problem is. You want to read all numbers and get the largest and smallest? I'm not understanding what you say is going wrong. I would try something like this: #include #include using namespace std; set nums; ifstream in(filename); while(in) { int n; in >> n; nums.insert(n); } set::iterator it = nums.begin(); cout << "first = " << (*it) << endl; int last; while(it != nums.end()) { last = (*it); it++; } cout << "last = " << last << endl; -- Rocky Dean Pulley

dr eu

I want to read all numbers and get the largest and smallest, but only from first 100 numbers in array[100], after that the same with another 100 numbers and so on.

David Crow

As you are reading in the numbers, if num_elements is a multiple of 100, then call biggest() and smallest(). Another way would be to read all of the numbers in the file, and call the biggest() and smallest() functions once for each group of 100 numbers, like:

big1 = biggest(table, 100); // search the first 100 numbers
big2 = biggest(&table[100], 100); // search the second 100 numbers
big3 = biggest(&table[200], 100); // search the third 100 numbers

Make sense?

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

Mattias G

If not using STL at all is an option, you might ask yourself why you store the numbers in an array in the first place. Just keep track of the smallest and largest numbers you fscanf'ed so far.

rocky_pulley

it sounds like he has to for a homework assignment. It sounds like a pretty lame homework assignment, must have been a math teacher turned programming teacher. -- Rocky Dean Pulley

dr eu

Yes, but how can i write big10489=biggest(&table[1048800], 100); ? This will take a lot of my time. And i don?t now, if file is so long?

dr eu

About homework you have right ! About teacher ... Who nows ? Any way could you help ?

rocky_pulley

I can't really do your homework for you, you won't learn anything that way. Besides, you are 90% there, just take the time and figure it out, you're almost done. -- Rocky Dean Pulley

dr eu

Yes, from that almost i am gona crazy. The result is O.K. (for all numbers in file). Help me please with 100, 200, ... elements in array !!!

David Crow

dr.eu wrote: Yes, but how can i write big10489=biggest(&table[1048800], 100); ? Exactly like that. This assumes that you have read at least 1,048,900 numbers from the file.

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

rocky_pulley

just use the same array, once you hit a number where (current_number % 100 == 0) then do your biggest/smallest check and reset current_number to 0, keep going on after that and it will just reuse your 100 item array. -- Rocky Dean Pulley

dr eu

In that case, i have to import another counter j: int j; bigj=biggest(&table[j], 100); Is right so?

dr eu

I done so: while (fscanf(in,"%f",&element) != EOF) { table[num_elements] = element; current_number=element; current_number%100==0; num_elements++; } but steel dont work propertly.

David Crow

How about:

while (...)
{
table[num_elements] = element;
num_elements++;
if ((num_elements % 100) == 0)
{
biggest(...);
smallest(...);
num_elements = 0;
}
}

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

dr eu

I try, but compiler return erors: too few arguments to function `float * biggest(float *, int)' at this point in file too few arguments to function `float * smallest(float *, int)' at this point in file

rocky_pulley

I don't mean to sound mean but you should really be able to figure that one out. -- Rocky Dean Pulley

dr eu

O.K., Thank you anyway for yours great help and good understanding. I'll try to do it well alone, but i'm not sure in access. Thanks again and goodbay !