/* Michael Kocovic 
 * Professor Hernandez
 * Lab 9: NumFromFile
 * CISC 1600
 *
 * Last edited: November 24th
 *
 *
 *
 *
 */
 
#include <iostream>
#include <fstream>
using namespace std;

//Precondition: instream is not currently associated with a file.
//Asks the user for a file name, then attempts to open the file on instream with the provided name.
//Exits the program if the file does not exist.
void openInFile(ifstream& inStream);

//Precondition: instream is associated with a file.
//For each line of numbers in your file, it reads the three numbers in and multiplies them by each other, i.e. 1*2*3 = 6.
//The resulting number is added to a running total, which is returned after all lines have been processed. 
int multAndSum(ifstream& inStream);

int main()
{
    ifstream inStream;
    //Opens file
    openInFile(inStream);
    //Prints out the calculation
    cout << "Result: " << multAndSum(inStream) << endl;

    return 0;
}
//Prompts user to enter file name, if file is incorrect, program will end
void openInFile(ifstream& inStream)
{
    string fileName;
    cout << "Insert file name: ";
    cin >> fileName;
    inStream.open(fileName);
    if (inStream.fail())
    {
        cout << "File error! Exiting program\n";
        exit(1);
    }
}
//Completes calculation for each line
int multAndSum(ifstream& inStream)
{
    int x, y, z;
    int totalAmount = 0;
    while (inStream >> x >> y >> z)
    {
        totalAmount += x * y * z;
    }
    
    return(totalAmount);
}

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Read inputs from stdin

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#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}