CPP program to check valid Identifier
C++ program to check the validity of any input string whether the inputted string is a valid identifier or invalid identifier. While developing this program we followed the basic rules of a valid identifiers in C/C++.
- All the valid identifiers should either start with alphabet or underscore (_).
- It should not contain any special character or punctuation marks.
The source code of this program checks these two basic rules.
/* Program to find out whether an inputed word is a valid identifier or not. made by : rakesh kumar */ #include #include #include #include using namespace std; int main() { char str[100]; int i; int valid = 1; // for checking validity //input phase cout<<"\n Enter any identifier :"; cin.getline(str,100); //processing phase cout<<"\n Entered Identifier :"<<str; if(isalpha(str[0])||str[0]=='_') valid = 1; else valid = 0; if(valid==1) { for(i=1;i<strlen(str);i++) { if(!(isalpha(str[i]) || isdigit(str[i])|| str[i]=='_')) {valid = 0; break;} } } //output phase if(valid == 0 ) cout<<"\n Invalid identifier"; else cout<<"\n Valid Identifier"; return 0; }
Above program was developed on Windows 10 Using Dev C++ IDE. The output of valid Identifier program is as follows.
