CODEWITHSUNDEEP
c++cprintf
suma
suma

Reputation: 728

Different output from sprintf function in c++

The sprintf is not displaying the string message appropriately. The message to be displayed is Value out of range. Range is -2147483648 and 2147483647. However it is printed as Value out of range. Range is -2147483648 and 0.

#include <iostream>
#include <string>

int main()
{
    __int64 tmpminVal = -2147483648;
    __int64 tmpmaxVal = 2147483647;

    std::string strTemp = "Value out of range. Range is %d and %i ";
    char buffer[100];
    int n = sprintf (buffer, strTemp.c_str(), tmpminVal,tmpmaxVal);
    strTemp = buffer;
    std::cout << strTemp << std::endl;
    return 0;
}

Please provide the reason why it is does so.

Upvotes: 0

Views: 596

Answers (3)

Bill Lynch
Bill Lynch

Reputation: 81926

So, as the other answers also say, you're invoking undefined behavior by passing a int64 to a format string expecting an int

Instead, you should use stdint.h and inttypes.h. On Linux, these will be included, and under Windows, you can include this project to use them: https://code.google.com/p/msinttypes/

An example use would be:

#include <iostream>
#include <string>
#include <inttypes.h>
#include <cstdint>

int main()
{
    int64_t tmpminVal = -2147483648;
    int64_t tmpmaxVal = 2147483647;

    std::string strTemp = "Value out of range. Range is %" PRId64 " and % " PRIi64 " ";
    char buffer[100];
    int n = sprintf (buffer, strTemp.c_str(), tmpminVal,tmpmaxVal);
    strTemp = buffer;
    std::cout << strTemp << std::endl;
    return 0;
}

You can also find some documentation about these header files at cppreference: http://en.cppreference.com/w/c/types/integer

Upvotes: 1

ST3
ST3

Reputation: 8946

You can find printf parameters.

As you see %d is signed integer, integer in this case means 32-bit. Go further to specifiers table and you will see, that to print 64-bit (long long) you need to use specifier ll, so you need %lld, not %d.

Your result (-2147483648 and 0) is Undefined Behaviour

Also as I see from comments, you want cross platform solution, so you should use long long instead of __int64, as this one is Windows type.

Upvotes: 2

Sergej Christoforov
Sergej Christoforov

Reputation: 1606

You passing two long long's to a function which expects two ints. Either change %d and %i to %ll or change __int64 to int.

Upvotes: 1

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