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can someone point out the error in the following code . I am using a naive approach of comparing both strings character by charcter and updating variable 'u' then comparing it with length of substring . If this is true then variable 'c' is updated by one unit.
Program in C++ :
#include<iostream>
#include<conio.h>
#include<string.h>
using namespace std;
int main()
{
char s[50],a[20];
cin.getline(s,50);
cin.getline(a,20);
//int l=strlen(s);
int p=strlen(a);
int i,c=0,j,u=0,k;
for(i=0;s[i]!='\0';i++)
{
if(a[i]='\0')
{break;}
if(s[i]==a[0])
{
for(j=i,k=0;a[k]!='\0';j++,k++)
{
if(s[j]==a[k])
{
u++;
//continue;
}
//else
//break;
}
//cout<<endl<<u;
if(u==p)
{
c++;
}
}
u=0;
}
cout<<endl<<"count "<<c;
getch();
}
For any kind of input combination , I am getting output as 0.
The problem is with this part:
if (a[i] = '\0')
{
break;
}
First, you are using = instead of ==, but that is not the entire problem. Either change a[i] to s[i], or comment out the entire block. I don't see why it is needed.
My tip and my coding convention to avoid your bug that you use = instead of == in:
if(a[i]='\0')
is to put the rvalue in the left side of the operand and the lvalue in the right side, like this:
if ('\0' == a[i])
this convention will avoid bugs like that(you will get a compilation error):
if ('\0' = a[i])
this code will generate a compilation error:
Error C2106 '=': left operand must be l-value
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Please someone run it , It runs fine for all uppercase values but if you include some x y or z the code breaks.
I found this in hackerrack and several test cases were passed but several failed.
#include<iostream>
using namespace std;
string caesarCipher(string, int);
int main() {
string s;
int places, length;
cin>>length;
cin>>s;
cin>>places;
if(places >26) {
places = places % 26 ;
}
s= caesarCipher(s,places);
cout<<s;
}
string caesarCipher(string S, int k){
for(int i=0;i<S.length();i++){
if(S[i]>='a' && S[i] <='z'){
S[i] = S[i]+k;
if(S[i]>'z'){
S[i]=S[i]-'z'+'a'-1;
}
}
else if(S[i]>='A' && S[i] <= 'Z'){
S[i] = S[i]+k;
if(S[i]>'Z'){
S[i]= S[i]-'Z'+'A'-1;
}
}
else
;
}
return S;
}```
To my own surprise, it looks like strings do not like certain values, not even temporarily.
If you use
S[i] = (S[i]-'a'+k)%26+'a'; instead of
S[i] = S[i]+k;, no value outside of a-z is ever written to the string, which as far as I tested avoids your problem.
An input of "Helloxyz" with a shift of 2 gets an output of "Jgnnqzab".
An the reverse, with a shift of 24 gets "Helloxyz" again.
With that, you do not need
if(places >26) {
places = places % 26 ;
}
/* ... */
if(S[i]>'z'){
S[i]=S[i]-'z'+'a'-1;
}
/* ... */
if(S[i]>'Z'){
S[i]= S[i]-'Z'+'A'-1;
}
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string longestCommonPrefix(vector<string>& strs) {
string res = "";
int i, j;
bool flag = true;
for(int i=0; i<strs[0].size(); i++)
{
for(int j=0; j<strs.size()-1; j++)
{
if(strs[j][i] == strs[j+1][i])
{
flag = true;
}
else
return res;
}
if(flag == true)
{
res += strs[0][i];
}
}
return res;
}
I was doing this leetcode question where we had to find the longest common prefix of given array of strings and then i got stuck at this i cant understand what is the meaning of this error, most of the test cases are passed so i don't think logic is wrong.Is there any corner cases i am missing?
Runtime Error Message:
Line 924: Char 9: runtime error: reference binding to null pointer of type 'std::__cxx11::basic_string, std::allocator >' (stl_vector.h)
Last executed input:
[]
Thanks in advance
Its null pointer exception. So you should check if str is null i.e. str=='" for each string in vector.
and return answer accordingly.
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I've just started coding in c++ and now I have an exercise that I can't do because the code seems to not work.
I've to find the max and the min with a sequence of n numbers (in this case i already know that they are 4). I've to use while.
I've just started so I don't know how return properly works...
there aren't syntactical errors but when I run it ask me the number but then it says that the algorithm ends with 0 value.
Here's the code, if you can help me thank you!
#include <iostream>
using namespace std;
main ()
{ float mag,min,i,a;
mag=0;
min=0;
i=0;
while (1)
{
if (i<5)
{ cout<<"insert a number"<<endl;
cin>>a;
if (i = 0)
{ mag=a;
min=a;
}
else
{ if (a<min)
{ min=a;
}
else
{ if (a>mag)
{ mag=a;
}
}
}
i=i+1;
}
else
{ cout<<"maggiore= "<<mag<<endl<<"min= "<<min<<endl;
}
return 0;
}
system ("pause");
}
I see at minimum one problem:
if (i = 0)
This is assignment of i to 0 and compare the result of assignment, which is always false if you assign a 0.
I believe you want only compare and not assign, so you have to use:
if ( i == 0 )
The next problem is
return 0;
This will always end the current function, if the function is main(), it will terminate your program. In your case, you can simply remove the return statement, as in main it will return 0 by default if the function ends.
But if you use
while (1)
without any return, your program runs endless. I don't know what is the expected behavior.
Rest looks fine.
Hint: Your indentation is a bit special. :-)
1st it should be i==0 not i=0 in the if
2nd you should place that return 0 after that cout maggiore or it will close after the first loop
3rd you don't need that system pause there. It does literally nothing. You should either remove it or place it exactly before the return.
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I'm using visual studio 2017, and coding under unreal engine coding standards, and its throwing an unhandled exception with invalid parameters passed to a function that considers them fatal. I can't figure it out, the VS2017 debugger is completely useless, and I'm pretty new to coding, can anyone throw me some suggestions? EDIT: The only thing that i can come close to finding is that it appears to be being cause by a string being out of range cause by an infinite loop somewhere in the function below.
FBullCowCount FBullCowGame::SubmitGuess(FText Guess)
{
// increment the turn number
MyCurrentTry++;
// setup a return variable
FBullCowCount BullCowCount;
// loop through all letters in the guess
int32 HiddenWordLength = MyHiddenWord.length();
for (int32 MHWChar = 0; MHWChar < HiddenWordLength; MHWChar++) {
// compare letters against the hidden word
for (int32 GChar = 0; GChar < HiddenWordLength; GChar++) {
//if they match then
if (Guess[MHWChar] == MyHiddenWord[MHWChar])
{
//increment bulls if they're in the same place
if (MHWChar == GChar) {
BullCowCount.Bulls++;
}
else {
BullCowCount.Cows++;
}
}
} //increment cows if not
}
return BullCowCount;
}
Your code comment says "loop through all letters in the guess", but your code loops through all letters of MyHiddenWord instead. That means that unless both Guess and MyHiddenWord have the exact same length, this:
if (Guess[MHWChar] == MyHiddenWord[MHWChar])
will at some point access an element of Guess that's out of range, and this is the likely cause of the exception, if FText happens to use a range-checked operator[].
What you probably want here is:
#include <algorithm>
// ...
auto HiddenWordLength = std::min(MyHiddenWord.length(), Guess.length());
It will limit the amount of letters to loop through to the shorter of the two strings.
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The variable steady_counter is intialized as a constant integer.
cout << steady_counter;
So long as i have the above statement anywhere before the following code, the function runs as expected and checks if an integer input is or is not a runaround number.
The problem is that when the cout line is not present, the constant integer changes within the below if statements. I tested this by printing steady_counter before entering the if-else, and then after the if-else.
Without the cout line, steady_counter changes to a 4 digit number.
for (int i = 0; i < 10; i++)
{
if (CheckArr[i])
{
num_of_unique++;
}
}
if ((steady_counter == num_of_unique) & (final == NumArr[0]) )
{
return true;
}
else
{
return false;
}
}
Any idea what's going on? Why do I require a cout line to maintain the constant integer steady_counter?
One obvious problem:
for (int i = counter; i > 0; i --)
NumArr[i] = -1;
This covers values from 1 to counter inclusive; while valid indexes for NumArr are from 0 to counter-1 inclusive. So you write outside the array, corrupting something else; possibly another local variable.
Either correct the off-by-one error in the index
NumArr[i-1] = -1;
or use a more canonical loop
for (int i = 0; i < counter; ++i)
or, for more of a C++ flavour,
std::fill(NumArr, NumArr+counter, -1);
There are likely to be further errors, which are better found by using your debugger than by asking people to read through all your code.