i came across this code snippet and do not understand. it recursively checks if an upper case char is present in a c++ string

Question

the base checks for null character but aren't c++ strings not supposed to be null terminated? should the base case check for length of the string?

#include <bits/stdc++.h> 
using namespace std; 

// Function to find string which has 
// first character of each word. 
char first(string str, int i=0) 
{ 
    if (str[i] == '\0') 
         return 0; 
    if (isupper(str[i]))  
            return str[i]; 
    return first(str, i+1); 
} 

// Driver code 
int main() 
{ 
    string str = "geeksforGeeKS"; 
    char res = first(str); 
    if (res == 0) 
        cout << "No uppercase letter"; 
    else
        cout << res << "\n"; 
    return 0; 
}

Standard guarantees, since C++11 (at least) that it is null terminated. — ChrisMM, Jan 11 '20 at 19:22
See this answer: https://stackoverflow.com/a/2037215/10686048 — ChrisMM, Jan 11 '20 at 19:25
@ChrisMM and even before C++11, most implementations were null terminated to simply the implementation of `c_str()` — Remy Lebeau, Jan 11 '20 at 19:28
@RemyLebeau But for example, in libstdc++ it wasn't. It was fairly widely used implementation even back then as far as I know. — eerorika, Jan 11 '20 at 19:33
1. if you do this, use iterators. 2. if you ignore (1), use a const reference; stop needlessly making copies of strings. — WhozCraig, Jan 11 '20 at 19:38
**Recommended reading:** [Why should I not #include ?](https://stackoverflow.com/q/31816095/560648) — Lightness Races in Orbit, Jan 11 '20 at 21:07

score 2 · Accepted Answer · answered Jan 11 '20 at 19:30

2

aren't c++ strings not supposed to be null terminated

std::string are (guaranteed to be) null terminated (since C++11).

should the base case check for length of the string?

It could be. But it doesn't need to be, because of the null termination.

answered Jan 11 '20 at 19:30

eerorika

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score 2 · Answer 2 · answered Jan 11 '20 at 19:58

2

aren't c++ strings not supposed to be null terminated?

Since C++11, std::string is guaranteed to be null-terminated.

should the base case check for length of the string?

Yes, if you want to handle strings that contain null characters.

For instance,

string str("ab\0cD", 5);

answered Jan 11 '20 at 19:58

Sid S

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It should be done that way anyway, because that is the interface of the type. The code in the question clearly originates from an old C implementation. Yes, `std::string` is null terminated due to an abstraction leak that had to be baked into the standard, but I wouldn't accept at code review any code that iterated a `std::string` as does that in the question. – Lightness Races in Orbit Jan 12 '20 at 14:28

i came across this code snippet and do not understand. it recursively checks if an upper case char is present in a c++ string

2 Answers2