Programming Forums > Application Development > C++

1cookie · Mar 22nd, 2008, 12:25 PM

hi

Write a c++ program, which uses File Input/Output and performs all of the following tasks;

a. reads 10 numbers {1; 2; 4.5; 2.5*10^10; -3; 0.5; 8*10^-10; -10;3.5} from one file.

b. reads another 5 numbers: {5*10^-6; 2; -7; 4.5; 5*10^5} from another file.

c. calculates the product of all 15 numbers and writes result to the screen and to a third file.

my code at the moment is:

 c++ Syntax (Toggle Plain Text) 
 
int main(){ 
 
float r[10], prod; 
fstream file_in; 
 
file_in.open("C:\\Users\\Cookson\\Desktop\\file1.txt",ios::in); 
 
int i =0; 
while(!file_in.eof()) 
{ 
file_in >> r[i];
 cout<<r[i]<<endl; 
i++; 
} 
 
 
}
int main(){ 

float r[10], prod; 
fstream file_in; 

file_in.open("C:\\Users\\Cookson\\Desktop\\file1.txt",ios::in); 

int i =0; 
while(!file_in.eof()) 
{ 
file_in >> r[i];
 cout<<r[i]<<endl; 
i++; 
} 


}

I have a file named: 'file1.txt' on my desktop, it has the first ten values in it (as above!).

When i compile and run the program, sure enough it reads the ten numbers into my array r[]. But instead of displaying ten numbers to the screen i get 11, I get an extra number that i don't want namely: 1.4013e-044!!

Why is this number appearing and for what reason??

help please.

I have a file named: 'file1.txt' on my desktop, it has the fist ten values in it (as above!).

When i compile and run the program, sure enough it reads the ten numbers into my array r[]. But instead of displaying ten numbers to the screen i get an extra number that i don't want namely: 1.4013e-044!!

Why is this number appearing and for what reason??

Ancient Dragon · Mar 22nd, 2008, 4:36 PM

>>Why is this number appearing and for what reason??
Because you are using feof() incorrectly on line 10. Rearrange your program like below. You rarely, if ever, have to use feof().

(Toggle Plain Text)

while(file_in >> r[i]) 
{ 
 cout<<r[i]<<endl; 
i++; 
}

1cookie · Mar 22nd, 2008, 5:42 PM

Quote:

Originally Posted by Ancient Dragon

>>Why is this number appearing and for what reason??
Because you are using feof() incorrectly on line 10. Rearrange your program like below. You rarely, if ever, have to use feof().

(Toggle Plain Text)

while(file_in >> r[i]) 
{ 
 cout<<r[i]<<endl; 
i++; 
}

thanks....

Mar 22nd, 2008, 12:25 PM	#1
1cookie Newbie Join Date: Mar 2008 Posts: 2 Rep Power: 0	file IO hi Write a c++ program, which uses File Input/Output and performs all of the following tasks; a. reads 10 numbers {1; 2; 4.5; 2.510^10; -3; 0.5; 810^-10; -10;3.5} from one file. b. reads another 5 numbers: {510^-6; 2; -7; 4.5; 510^5} from another file. c. calculates the product of all 15 numbers and writes result to the screen and to a third file. my code at the moment is: c++ Syntax (Toggle Plain Text) int main(){ float r[10], prod; fstream file_in; file_in.open("C:\\Users\\Cookson\\Desktop\\file1.txt",ios::in); int i =0; while(!file_in.eof()) { file_in >> r[i]; cout<<r[i]<<endl; i++; } } int main(){ float r[10], prod; fstream file_in; file_in.open("C:\\Users\\Cookson\\Desktop\\file1.txt",ios::in); int i =0; while(!file_in.eof()) { file_in >> r[i]; cout<<r[i]<<endl; i++; } } I have a file named: 'file1.txt' on my desktop, it has the first ten values in it (as above!). When i compile and run the program, sure enough it reads the ten numbers into my array r[]. But instead of displaying ten numbers to the screen i get 11, I get an extra number that i don't want namely: 1.4013e-044!! Why is this number appearing and for what reason?? help please. I have a file named: 'file1.txt' on my desktop, it has the fist ten values in it (as above!). When i compile and run the program, sure enough it reads the ten numbers into my array r[]. But instead of displaying ten numbers to the screen i get an extra number that i don't want namely: 1.4013e-044!! Why is this number appearing and for what reason??

Mar 22nd, 2008, 4:36 PM	#2
Ancient Dragon PFO God In Training Join Date: Jun 2005 Location: near St Louis, MO. (USA) Posts: 496 Rep Power: 4	Re: file IO >>Why is this number appearing and for what reason?? Because you are using feof() incorrectly on line 10. Rearrange your program like below. You rarely, if ever, have to use feof(). (Toggle Plain Text) while(file_in >> r[i]) { cout<<r[i]<<endl; i++; } while(file_in >> r[i]) { cout<<r[i]<<endl; i++; } __________________ I Like Ike. Vote for Dwight Eisenhower this November. --This message brought to you by the the Procrastinators Club Of America.

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Programming Forums > Application Development > C++

file IO