//I am writing a program that converts from one unit like mm to another e.g cm. The program should prompt invalid unit when something other than mm, cm, m or km is entered as the unit to be converted from or unit to be converted to. The problem is how I initialize the units. When debugging, input ends the program. What do I do?

//Program to shows conversion of units

```
#include <iostream> // for cin, cout
#include <string>
#include <cmath>
using namespace std;
int main()
{
char init_unit[2], sec_unit[2]; //declaration of the conversion units
double conv_val; //declaration of the number to be converted
// Welcome message
cout<< "km m cm mm km m cm mm km m cm mm km m cm mm km m cm mm\n"
<< "| |\n"
<< "| Welcome to Topiloe Metric unit converter |\n"
<< "| |\n"
<< "km m cm mm km m cm mm km m cm mm km m cm mm km m cm mm\n\n";
//request conversion unit
cout<<"Enter initial conversion unit (mm, cm, m, km): \n"; //user enters units
cin>>init_unit;
if (init_unit != 'mm'||init_unit !='cm'||init_unit !='m'||init_unit !='km')
{
cerr<<"--> Sorry, unit to convert from is invalid\n"
<<"Thank you for using Topiloe Metric Unit converter Program\n";
}
else
{
cout<<"Enter unit to convert to (mm, cm, m, km): \n"; //user enters units
cin>>sec_unit;
}
if (sec_unit != 'mm'||sec_unit != 'cm'||sec_unit != 'm'||sec_unit != 'km')
{
cout<<"--> Sorry, unit to convert TO is invalid\n"
<<"Thank you for using Topiloe Metric Unit converter Program\n";
}
else if (init_unit == 'mm' && sec_unit == 'cm')
{
cout<<"Enter numerical value to convert: \n";
cin>>conv_val;
cout<<"Result of conversion: "<<conv_val<<" is equivalent to "<<conv_val*10<<" "<<sec_unit<<endl //cm=mm*10
<<"Thank you for using Topiloe Metric Unit converter Program\n";
}
else if (init_unit == 'mm' && sec_unit == 'm')
{
cout<<"Enter numerical value to convert: \n";
cin>>conv_val;
cout<<"Result of conversion: "<<conv_val<<" is equivalent to "<<conv_val*100<<" "<<sec_unit<<endl //m=mm*100
<<"Thank you for using Topiloe Metric Unit converter Program\n";
}
else if (init_unit == 'mm' && sec_unit == 'km')
{
cout<<"Enter numerical value to convert: \n";
cin>>conv_val;
cout<<"Result of conversion: "<<conv_val<<" is equivalent to "<<conv_val*100000<<" "<<sec_unit<<endl //km=100000*mm
<<"Thank you for using Topiloe Metric Unit converter Program\n";
}
else if (init_unit == 'cm' && sec_unit == 'mm')
{
cout<<"Enter numerical value to convert: \n";
cin>>conv_val;
cout<<"Result of conversion: "<<conv_val<<" is equivalent to "<<conv_val/10<<" "<<sec_unit<<endl //cm=mm*10
<<"Thank you for using Topiloe Metric Unit converter Program\n";
}
else if (init_unit == 'cm' && sec_unit == 'm')
{
cout<<"Enter numerical value to convert: \n";
cin>>conv_val;
cout<<"Result of conversion: "<<conv_val<<" is equivalent to "<<conv_val*10<<" "<<sec_unit<<endl //cm=m*10
<<"Thank you for using Topiloe Metric Unit converter Program\n";
}
else if (init_unit == 'cm' && sec_unit == 'mm')
{
cout<<"Enter numerical value to convert: \n";
cin>>conv_val;
cout<<"Result of conversion: "<<conv_val<<" is equivalent to "<<conv_val/10<<" "<<sec_unit<<endl //cm=mm*10
<<"Thank you for using Topiloe Metric Unit converter Program\n";
}
else if (init_unit == 'cm' && sec_unit == 'm')
{
cout<<"Enter numerical value to convert: \n";
cin>>conv_val;
cout<<"Result of conversion: "<<conv_val<<" is equivalent to "<<conv_val*10<<" "<<sec_unit<<endl //m=cm*10
<<"Thank you for using Topiloe Metric Unit converter Program\n";
}
else if (init_unit == 'cm' && sec_unit == 'km')
{
cout<<"Enter numerical value to convert: \n";
cin>>conv_val;
cout<<"Result of conversion: "<<conv_val<<" is equivalent to "<<conv_val*10000<<" "<<sec_unit<<endl //km=10000*cm
<<"Thank you for using Topiloe Metric Unit converter Program\n";
}
else if (init_unit == 'm' && sec_unit == 'mm')
{
cout<<"Enter numerical value to convert: \n";
cin>>conv_val;
cout<<"Result of conversion: "<<conv_val<<" is equivalent to "<<conv_val/100<<" "<<sec_unit<<endl //m=mm*100
<<"Thank you for using Topiloe Metric Unit converter Program\n";
}
else if (init_unit == 'm' && sec_unit == 'cm')
{
cout<<"Enter numerical value to convert: \n";
cin>>conv_val;
cout<<"Result of conversion: "<<conv_val<<" is equivalent to "<<conv_val/10<<" "<<sec_unit<<endl //m=cm*10
<<"Thank you for using Topiloe Metric Unit converter Program\n";
}
else if (init_unit == 'm' && sec_unit == 'km')
{
cout<<"Enter numerical value to convert: \n";
cin>>conv_val;
cout<<"Result of conversion: "<<conv_val<<" is equivalent to "<<conv_val*1000<<" "<<sec_unit<<endl //km=1000*m
<<"Thank you for using Topiloe Metric Unit converter Program\n";
}
else if (init_unit == 'km' && sec_unit == 'mm')
{
cout<<"Enter numerical value to convert: \n";
cin>>conv_val;
cout<<"Result of conversion: "<<conv_val<<" is equivalent to "<<conv_val/100000<<" "<<sec_unit<<endl //km=100000*mm
<<"Thank you for using Topiloe Metric Unit converter Program\n";
}
else if (init_unit == 'km' && sec_unit == 'cm')
{
cout<<"Enter numerical value to convert: \n";
cin>>conv_val;
cout<<"Result of conversion: "<<conv_val<<" is equivalent to "<<conv_val/10000<<" "<<sec_unit<<endl //km=10000*cm
<<"Thank you for using Topiloe Metric Unit converter Program\n";
}
else if (init_unit == 'km' && sec_unit == 'm')
{
cout<<"Enter numerical value to convert: \n";
cin>>conv_val;
cout<<"Result of conversion: "<<conv_val<<" is equivalent to "<<conv_val/1000<<" "<<sec_unit<<endl //km=1000*m
<<"Thank you for using Topiloe Metric Unit converter Program\n";
}
}
```