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Closed 10 years ago.
I am using C++ string functions in cocos2dx. I have the following string CorrectAns = "below".
for(int i = 0; i<CorrectAns.size();i++)
{
CorrectAns.replace(i,i,"?");
}
This function should return my string as "?????", but its returning only 4 charcters ie "????".
When I write like this,
for(int i = 0; i<CorrectAns.size();i++)
{
if(i == 0)
{
CorrectAns.replace(i,i,"?");
}
}
It just crashes.
and works fine only when I write it as " CorrectAns.replace(i,i+1,"?");"
Why is the function working this way?? Can anyone help me please??
string& replace ( size_t pos1, size_t n1, const string& str );
For the versions with parameters pos1 and n1, the section replaced
begins at character position pos1 and spans for n1 characters within
the string.
So you should use
for(int i = 0; i<CorrectAns.size();i++)
{
CorrectAns.replace(i,1,"?");
}
Mb it will be more usefull use something like
CorrectAns.assign(CorrectAns.size(), '?');
Related
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Closed 9 years ago.
I wanted to ask, i formulated this code to solve a question, but count does not seem to provide the right value.
Any advice.Any help appreciated. Thanks.
#include<iostream.h>
#include<conio.h>
void main()
{
int count;
for(int a=1;a<125;a++)
for(int m=1;m<125;m++)
for(int n=1;n<125;n++)
{
if(a*(m+n+2)==249-m)
{
cout<<"a = "<<a<<" m = "<<m<<" n = "<<n<<"\n";
count=count+1;
}
}
cout<<"count = "<<count<<"\n";
getch();
}
You do not init the count. Remember to set int count = 0;.
Your compiler will warn you about this and save you the trouble of debugging or asking if you only let it. (from #chris)
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Closed 10 years ago.
In Windows, one can use structured exception handling in C to write a pseudo-loop that prints all numbers from 1 to 1000 like this:
int n = 0;
__try {
*(int *)0 = 0;
}
__except(printf("%i\n", ++n), n < 1000 ? -1 : 1) {
}
I wonder if there are also other ways in C/C++ to create a loop that isn't trivial to detect if you search the code for the usual suspect keywords for, while and goto.
In C++, a simple lambda can do that:
std::function<void(int,int)> print = [&](int from, int to)
{
std::cout << from << " ";
if ( from < to ) print(++from, to);
};
print(1, 1000);
It will print all integers from 1 to 1000. And it doesn't use for, while or goto.
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Closed 10 years ago.
What is the check_union256d function?
It's placed in following code:
/* { dg-do run } */
/* { dg-require-effective-target avx } */
/* { dg-options "-O2 -mavx" } */
#include "avx-check.h"
void static
avx_test (void)
{
int i;
union256d u, s1, s2;
double e [4];
s1.x = _mm256_set_pd (2134.3343,1234.635654,453.345635,54646.464356);
s2.x = _mm256_set_pd (41124.234,2344.2354,8653.65635,856.43576);
u.x = _mm256_div_pd (s1.x, s2.x);
for (i = 0; i < 4; i++)
e[i] = s1.a[i] / s2.a[i];
if (check_union256d (u, e))
abort ();
}
It's from Intel AVX which is:
a new 256 bit instruction set extension to SSE and is designed for applications that are Floating Point (FP) intensive.
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Closed 11 years ago.
Hi guys i know what NaN(let me say i know the acronym stands for Not a Number) is but i don't understand why C++ returns it - The following is the approximation of the mathematical constant e - When using the debugger the functions evaluate fine, it's when writing to the console that it returns NaN
Thanks for any feedback
double Factorial(int k)
{
if(k == 0)
return 1;
int value = 1;
for(int i = k; i > 0; i--)
value *= k;
return value;
}
double e(int p)
{
double value = 0.0;
for(int i = 0; i < p; i++)
{
value += 1/Factorial(i);
}
}
You don't return a value in your e function.
You forgot to return value at the end of e. I don't know when c++ stopped warning about missing returns.
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Closed 11 years ago.
I made a Matrix class on my own. but there is interesting problem when overloading + operator.
Matrix Matrix::operator+ (Matrix& operand)
{
if(row_size == operand.row_size && col_size == operand.col_size)
{
Matrix temp(row_size, col_size);
for(int i = 0; i < col_size; i ++)
{
for(int j = 0; j < row_size; j ++)
{
temp[i][j] = data_list[i][j] + operand.data_list[i][j];
}
}
return temp;
}
else
throw Error::Matrix_error(0);
}
When I do
matrix + matrix2;
on main function, it seems like the program is in a infinite loop. So, I just debugged it and found out that the code stops at return temp; part.
I have no idea why this function cannot return temp since return type of operator+ is Matrix.
Plus, this code totally works well when I compile in a RELEASE mode (visual studio 2010). However it does not work when I compile in a DEBUG mode.
The problem was I miss created copy constructor. It looks like it fell on infinite loop at copy constructor but the debugger didn't catch it.