Out-of-bounds access (ARRAY_VS_SINGLETON)
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Thread: Out-of-bounds access (ARRAY_VS_SINGLETON)

  1. #1
    Join Date
    May 2010
    Posts
    12

    Out-of-bounds access (ARRAY_VS_SINGLETON)

    Need little help..

    #include <iostream>
    int main() {
    int bit = 1;
    int init = 0xf ^ (1 << bit);
    char* c = new char(2);
    sprintf(c, "%x", init);
    std::string initVal = std::string("4'h") + c;
    std::cout << initVal << std::endl;
    }

    Above code is compiling as I expect it to be.
    Problem is when I run ******** on it, it prompts me the following message:

    Out-of-bounds access (ARRAY_VS_SINGLETON). Passing "c" to function "operator +(HSTString const &, char const *)" which uses it as an array. This might corrupt or misinterpret adjacent memory locations


    I am out of ideas for now. Can champs here figure out what I am doing wrong?

  2. #2
    Join Date
    Jan 2006
    Location
    Singapore
    Posts
    6,276

    Re: Out-of-bounds access (ARRAY_VS_SINGLETON)

    You cannot store the result of sprintf call into the location pointed to by c in the first place because you only allocated a single char, initialising it with a value of 2. Perhaps you wanted to use new char[2] instead, but that would still be rather unnecessary. Instead, you might as well just use the standard C++-specific facilities, e.g.,
    Code:
    #include <iostream>
    #include <iomanip>
    #include <string>
    #include <sstream>
    
    int main()
    {
        unsigned int bit = 1;
        unsigned int init = 0xf ^ (1u << bit);
        std::stringstream ss;
        ss << "4'h" << std::hex << init;
        std::string initVal = ss.str();
        std::cout << initVal << std::endl;
    }
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  3. #3
    Join Date
    May 2010
    Posts
    12

    Re: Out-of-bounds access (ARRAY_VS_SINGLETON)

    That is exactly clarification I was looking for.. I should have figured that out myself.
    Thanks for your help..

    Quote Originally Posted by laserlight View Post
    You cannot store the result of sprintf call into the location pointed to by c in the first place because you only allocated a single char, initialising it with a value of 2. Perhaps you wanted to use new char[2] instead, but that would still be rather unnecessary. Instead, you might as well just use the standard C++-specific facilities, e.g.,
    Code:
    #include <iostream>
    #include <iomanip>
    #include <string>
    #include <sstream>
    
    int main()
    {
        unsigned int bit = 1;
        unsigned int init = 0xf ^ (1u << bit);
        std::stringstream ss;
        ss << "4'h" << std::hex << init;
        std::string initVal = ss.str();
        std::cout << initVal << std::endl;
    }

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