print sum if all inputs are valid otherwise print "Invalid" in c++

Question

The problem is to print sum of all integers in one input line.If any of the input is not valid print "Invalid". This is the code --> C++ Code Link

The problem with the code is that it doesn't produces output if input > 9

.How should I approach here?

input : 1 2 3 14
output : 11 //which is wrong
input : 1 a 2 b
output : Invalid

Please avoid posting link to external sites. Edit your question and paste the code in your question. — Barmak Shemirani, Jun 07 '16 at 21:37
@BarmakShemirani Telling people to paste the code here usually yields still OT code dumps. Better tell them to post a [mcve] instead. — Baum mit Augen, Jun 07 '16 at 21:39
What do you mean the 'above' input gives you a compilation error? What's the input you're talking about? How do you define valid? The input you posted compiles fine. — Toma Radu-Petrescu, Jun 07 '16 at 21:59

score 1 · Accepted Answer · answered Jun 07 '16 at 21:41

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At line 16 of your code:

for(int i = 0 ; i < v.size() ; ++i)

You compare i, which is a signed integer, to v.size(), which is of the unsigned type size_t. Replace int by size_t:

for(size_t i = 0 ; i < v.size() ; ++i)

answered Jun 07 '16 at 21:41

shrike

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Ahh yes! Thank you very much.But the problem with the code is that it produces output only if input is a single digit.What if input is > 9 ? – close2zero Jun 07 '16 at 22:02
@krishnakeshav If you have another question, please post a new question. – Baum mit Augen Jun 07 '16 at 22:07

score 0 · Answer 2 · answered Jun 07 '16 at 21:53

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In the for loop use unsigned instead of int and it will solve the problem. You are comparing i with is signed int with an unsigned v.size().

answered Jun 07 '16 at 21:53

kemis

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This also works.However, I would prefer using 'size_t'. – close2zero Jun 07 '16 at 22:11

score 0 · Answer 3 · edited May 23 '17 at 12:17

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You are trying to store 14 in a char which will not work! Everything will be fine with single digit numbers (0,1,2,3,4,5,6,7,8,9) because they are seen as a single character, but 14 contains two characters, so firstly 1 will be added in the vector, then 4. So, the answer 11 is correct because 1+2+3+1+4=11! You can either use this solution: https://stackoverflow.com/a/289372/3185860 or the strtok alternative to divide the input string and get the numbers (in this case, the ' ' will be your delimiter character) or parse the input in another way to store the numbers in an int variable.

Edit: I see you still can't understand what you have to do. It took 2 minutes to modify the response from the link I commented below ( https://stackoverflow.com/a/1321175/3185860 ) to solve your problem... Next time, please spend more time trying to solve it yourself.

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

size_t ReadNumbers( const string & s, vector <int> & v ) {
    istringstream is( s );
    int n;

    for(int i=0; i<s.size(); i++) if(isalpha(s[i]) && s[i]!=' ') return 0;

    while( is >> n ) {
        v.push_back( n );
    }

    return v.size();
}

int main() {
    int sum=0;
    string s;
    vector <int> v;
    getline( cin, s );
    ReadNumbers( s, v );
    if(v.size()==0){ cout<<"Invalid\n"; return 0;}
    else{
        for ( int i = 0; i < v.size(); i++ ) {
            sum = sum + v[i];
        }
    }

    cout<<sum<<'\n';
    return 0;
}

edited May 23 '17 at 12:17

Community

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answered Jun 07 '16 at 22:16

Toma Radu-Petrescu

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can you show me example code? – close2zero Jun 07 '16 at 22:22
Look at the link i posted in the answer. You will have to store the whole input in a string (not in a vector of characters), then do what the link says, but instead of '-', you will have ' ' and when you find a number, convert it to an int and add it to the sum. – Toma Radu-Petrescu Jun 07 '16 at 22:31
This answer does what you want: http://stackoverflow.com/a/1321175/3185860 – Toma Radu-Petrescu Jun 08 '16 at 07:01
Tried link given by you.It stops accepting input if it is not valid.But how am I suppose to check for end of line or if input is invalid? – close2zero Jun 08 '16 at 14:39
@krishnakeshav look at the edited answer. Next time, try to think more. This is not a place to solve homeworks. – Toma Radu-Petrescu Jun 08 '16 at 15:32
Also, a thank you is more than welcome. – Toma Radu-Petrescu Jun 09 '16 at 13:12

print sum if all inputs are valid otherwise print "Invalid" in c++

3 Answers3