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Variable being used without being initialized

raaj5671 (34)
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#include<iostream>
#include<iomanip>
#include<fstream>
#include<string>
#include<cmath>
using namespace std;
int studentdetails_mean();
double standard_deviation();
void barchart();

int studentdetails_mean(){
	ofstream outfile;
	outfile.open("output.txt");
	string student_name;
	int exam_marks[5],sum=0;
	int mean;
	for(int x=0;x<5;x++){
			cout<<"Please enter the student name: ";
			cin>>student_name;
			cout<<"Please enter the examination marks: ";
			cin>>exam_marks[x];
			sum=sum+exam_marks[x];
	}
	mean=sum/5;
	outfile<<"The mean is "<<mean<<endl;
	outfile.close();
	return mean;
}

double standard_deviation(){
	ofstream outfile;
	outfile.open("output.txt");
	int exam_marks[5],students=5,mean;
	double std_dev=0,sox_m,s=0;
	int nminus=4;
	mean;
	for(int ii=0;ii<students;ii++){
		s=s+((exam_marks[ii]-mean)*(exam_marks[ii]-mean));
	}
	std_dev=sqrt(s/nminus);
	cout<<"The result is: "<<std_dev<<endl;
	outfile<<"The standard deviation is: "<<std_dev<<endl;
	outfile.close();
	return std_dev;
}

void barchart(){
	ofstream outfile;
	outfile.open("output.txt");
	int G_A=0,G_B=0,G_C=0,G_D=0,G_F=0,exam_marks[5];
	for(int x=0;x<5;x++){
	if(exam_marks[x]<=39.9){
		cout<<"Grade F"<<setw(15)<<endl;  
		outfile<<"Grade F";
		cout<<"*"<<endl;
		outfile<<"*"<<endl;
		G_F++;
	}else if(exam_marks[x]<=49.9){
		cout<<"Grade D"<<setw(15)<<endl;
		outfile<<"Grade D";
		cout<<"*"<<endl;
		outfile<<"*"<<endl;
		G_D++;
	}else if(exam_marks[x]<=69.9){
		cout<<"Grade C"<<setw(15)<<endl;
		outfile<<"Grade C";
		cout<<"*"<<endl;
		outfile<<"*"<<endl;
		G_C++;
	}else if(exam_marks[x]<=79.9){
		cout<<"Grade B"<<setw(15)<<endl;
		outfile<<"Grade B";
		cout<<"*"<<endl;
		outfile<<"*"<<endl;
		G_B++;
	}else if(exam_marks[x]<=100){
		cout<<"Grade A"<<setw(15)<<endl;
		outfile<<"Grade A";
		cout<<"*"<<endl;
		outfile<<"*"<<endl;
		G_A++;
	}
	outfile.close();
	}
}
int main(){
	int number_stud[5],sum=0;
	double exam_marks[5],mean=0;
	string student_name;
	ifstream infile; // input file
	ofstream outfile; //output file
	infile.open("input.txt"); 
	outfile.open("output.txt");
	
	if(!outfile){  //if cannot open the file
		cout<<"Cannot open file."<<endl;
		return 1;
	}

	string data;

	while(!infile.eof()){
		getline(infile,data);
		cout<<data<<endl;  //output to terminal window
		}
	
	studentdetails_mean();
	standard_deviation();
	barchart();
	infile.close();
	outfile.close();

	system("pause");
	return 0;
}

its showing Run-Time Check Failure #3 - The variable 'mean' is being used without being initialized.
can anyone help me on this ASAP
MiiNiPaa (8886)
Line 38: You didn't assign "mean" anything before, so it will hold anything what were in memory before (essentyally it's random).
ajh32 (659)
What tools are you using? Can you not put breakpoints in your code and debug and see where the problem is located?

BTW at line#36 you have used the local variable named 'mean' without it having been initialised, although it doesn't appear to be doing anything.
raaj5671 (34)
i am using microsoft visual studio 2012...
raaj5671 (34)
what value should i use for the mean?
i dont have idea.. help pls
MiiNiPaa (8886)
what are you trying to accomplish in the first place? What should be "mean" value in your algorythm? I mean, it's you who write it, so you should kmow more than us.
raaj5671 (34)
well i m creating a program which will show the mean and the standard deviation of the student marks.
this is the question given..

Statistical Calculator

Write a program to read in a sequence of examination mark from a text file named as input.txt and produce the mean, and standard deviation of the marks. Your program should also produce a bar chart for each grade where the range of mark is given as below.

Grade Marks Range
A 80-100
B 70-79.9
C 50-69.9
D 40-49.9
F 0-39.9

Output the result to another text file named as output.txt.
ajh32 (659)
i am using microsoft visual studio 2012


Well you should be able to spot issues such as variable x hasn't been initialised. Have you attempted to debug with breakpoints?

How about 5 for the value of mean?
raaj5671 (34)
i am still new to c++ can you pls tell me how to debug with breakpoints...
ajh32 (659)
Try searching the web with such terms as:

"visual studio debug breakpoint"
raaj5671 (34)
tq very much for the help... now my standard deviation code is not working...
ajh32 (659)

tq very much for the help... now my standard deviation code is not working...


When you say "not working" what do you mean? Did you try adding a few breakpoints?
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