/*this program to difer between number ,
variable and operation*/
#include<iostream.h>
#include<string.h>
#include<conio.h>
int state=1,index1=0;
char w[50];
int index2=0,l;
char st[10];
void putt(int);
int digits()
{
if(w[index1]>=’0′ && w[index1]<=’9′)
{
st[index2++]=w[index1++];
return 1;
}
else
return 0;
}
int var()
{
if((w[index1]>=’A’ && w[index1]<=’Z') ||
(w[index1]>=’a’ && w[index1]<=’z'))
{
st[index2++]=w[index1++];
return 1;
}
else
return 0;
}
int sign()
{
if(w[index1]==’-')
{
st[index2++]=w[index1++];
return 1;
}
else
return 0;
}
int oper()
{
if(w[index1]==’+’ || w[index1]==’-’ ||
w[index1]==’*’ ||w[index1]==’/')
{
st[index2++]=w[index1++];
putt(2);
return 1;
}
else
return 0;
}
void err()
{
if(state==2)
cout<<"error in position :"<<index1<<"it is not
number or variable or not both\n";
else
if(state==4)
cout<<"error in position :"<<index1<<"it is not
operation or did not found number after
operation\n";
index1=l+1;
}
void main()
{
cin>>w;
l=strlen(w);
w[l]=”;
while(index1<=l)
{
switch(state)
{
case 1:
if(digits())
