Question

Write a program in c++ that generates a 100 random numbers between 1 and 1000 and writes them to a data file called "randNum.dat". Then re-open the file, read the 100 numbers, print them to the screen, and find and print the minimum and maximum values.

Specifications:

If your output or input file fails to open correctly, print an error message that either states:

   Output file failed to open
   Input file failed to open

depending on whether the output or input file failed to open.

Prompt the user for a seed value so that your program can interface with the grader program.

When printing the numbers to the data file, print a return character after each number in the file.

When reading in the numbers from the file and printing them to the screen, use the following output:

   Num XXX: YYYY

where XXX indicates which number is being printed out, and YYYY represents the actual random value. For instance, if you input a seed value of 42, then for the 91st number the following should be printed to the screen:

   Num  91:  923

Use the setw() function with a width of 3 to indicate which number is being printed out, and use a width of 4 to print the actual value so that everything is right justified. Use a width of 4 as well when printing the minimum and maximum values.

As an example, if you execute the program with the following underlined inputs, the output will be:

   Enter Seed: 42

   Num   1:  167
   Num   2:  741
   Num   3:  882
   ...
   Num  67:  451
   Num  68:  361
   ...
   Num  99:  652
   Num 100:   37

   Min:   13
   Max:  996
   ~>

Answer 1

// C++ program to perform operations on file

#include <iostream>
#include <cstdlib>
#include <fstream>
#include <iomanip>

using namespace std;

int main()
{
// filename
const string filename = "randNum.dat";
int seed, num, max, min, count;

// create and open the file
ofstream fout(filename);

// file open failed, display error and exit the program
if(fout.fail()){
cout<<"Output file failed to open"<<endl;
return 0;
}

// input the seed
cout<<"Enter Seed: ";
cin>>seed;

// set the seed value for random number generator
srand(seed);

// loop to generate 100 random integers between [1,1000] and output to file
for(count=1;count<=100;count++)
{
num = rand()%1000 + 1;
fout<<num;
if(count < 100) // not the last integer, display a new line
fout<<endl;

}

fout.close(); // close the output file

// re-open the file in read mode
ifstream fin(filename);

// file open failed, display error and exit the program
if(fin.fail())
{
cout<<"Input file failed to open"<<endl;
return 0;
}

count = 0; // reset count to 0

// loop till the end of file
while(!fin.eof())
{
// read an integer
count++;
fin >> num;

// display the integer read
cout<<"Num"<<right<<setw(3)<<count<<":"<<right<<setw(4)<<num<<endl;
// this is the first integer read, set max and min to num
if(count == 1)
{
max = num;
min = num;
}
else // not the first integer read
{
// num > max, update max to num
if(num > max)
max = num;
else if(num < min) // num < min, update min to num
min = num;
}
}

fin.close(); // close the input file

// display the minimum and maximum number
cout<<endl<<"Min: "<<right<<setw(4)<<min<<endl;
cout<<"Max: "<<right<<setw(4)<<max<<endl;
return 0;
}

//end of program

Output:

Enter Seed: 42 Num 1: 176 Num 2: 401 Num 3: 870 Num 4: 57 Num 5: 84 Num 6: 880 Num 7: 17 Num 8: 645 Num 9: 810 Num 10: 770 Num 11: 410 Num 12: 951 Num 13: 472 Num 14: 100 Num 15: 337 Num 16: 226 Num 17: 189 Num 18: 713 Num 19: 352 Num 20: 677 Num 21: 908 Num 22: 731 Num 23: 687 Num 24: 608 Num 25: 191 Num 26: 41 Num 27: 337 Num 28: 92 Num 29: 446 Num 30: 716 Num 31: 183 Num 32: 598 Num 33: 889 Num 34: 446 Num 35: 907 Num 36: 148 Num 37: 650 Num 38: 173 Num 39: 168 Num 40: 556 Num 41: 470 Num 42: 924 Num 43: 344 Num 44: 369 Num 45: 861 Num 46: 300 Num 47: 182 Num 48: 350

Num 55: 488 Num 56: 703 Num 57: 746 Num 58: 631 Num 59: 68 Num 60: 270 Num 61: 777 Num 62: 636 Num 63: 539 Num 64: 172 Num 65: 103 Num 66: 387 Num 67: 466 Num 68: 906 Num 69: 522 Num 70: 98 Num 71: 693 Num 72: 77 Num 73: 626 Num 74: 768 Num 75: 698 Num 76: 846 Num 77: 110 Num 78: 14 Num 79: 643 Num 80: 680 Num 81: 755 Num 82: 724 Num 83: 664 Num 84: 465 Num 85: 263 Num 86: 759 Num 87: 92 Num 88: 141 Num 89: 393 Num 90: 834 Num 91: 847 Num 92: 568 Num 93: 43 Num 94: 18 Num 95: 228 Num 96: 515 Num 97: 794 Num 98: 167 Num 99: 283 Num100: 849 Min: 14 951 Max:

Output file : randNum.dat

176 401 870 57 84 880 17 645 810 770 410 951 472 100 337 226 189 713 352 677 908 731 687 608 191 41 337 92 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 53 446 716 183 598 889 446 907 148 650 173 168 556 470 924 344 369 861 300 182 350 936 737 533 24 410 871 488

50 51 52 53 54 55 56 57 5g 59 石 61 石之 E3 64 65 E6 737 533 24 410 871 488 703 746 631 68 270 777 636 539 172 103 387 466 06 522 8 693 了 62 69 77 70 71 72 73 74 75 76 77 了三 79 30 31 82 3 24 85 Bb 了 SE 29 So 91 92 93 94 95 96 97 626 768 698 246 110 14 643 680 755 724 664 465 263 759 92 141 393 334 847 568 43 18 222 515 794 167 283 849 96 99 100