why would std::string assignment operator fail?

[korgoth28]

I call a function

theMap[x][y].moveUnitOn('M', c, "a merchant", UnitPointer(&(merchantList[merchantNum])));which looks like this


void Tile::moveUnitOn(char g, int c, string d, UnitPointer unit)
{
bgGraphic = graphic;
graphic = g;
bgColorPair = colorPair;
colorPair = c;
bgDescription = description;
description = d;
occupyingUnit = unit;
}
and I get a segmentation fault. gdb tells me the problem is with bgDescription = description. bgDescription is just a data member of Tile. Specifically the error is:


#0 0x7ffff773019a ??() (/usr/lib/x86_64-linux-gnu/libstdc++.so.6:??)
#1 0x7ffff77315c6 std::string::assign(std::string const&) () (/usr/lib/x86_64-linux-gnu/libstdc++.so.6:??)
#2 0x4032ec Tile::moveUnitOn(this=0x7ffffffa33c0, g=77 'M', c=5, d=..., unit=...) (/home/mike/Desktop/klepto/Tile.cpp:13)
#3 0x40263c Player::hireMerchant(this=0x7ffffffa2e80, c=5, theMap=0x7ffffff1a300) (/home/mike/Desktop/klepto/Player.cpp:35)
#4 0x404246 main(argc=1, argv=0x7fffffffe268) (/home/mike/Desktop/klepto/main.cpp:265)


The code worked fine until I changed the data member occupyingUnit from type Merchant* to unitPointer. Thanks in advance.

[movieman]

Are you running off the end of your array when you index by x and y?

If bgDescription is not a properly initialised string object, anything could happen when you try to copy a string into it (e.g. it's going to try to free the old string data, which will just be a garbage pointer).

[MadCow108]

most likely some memory corruption or overflow
what does valgrind say?

[korgoth28]

Are you running off the end of your array when you index by x and y?

If bgDescription is not a properly initialised string object, anything could happen when you try to copy a string into it (e.g. it's going to try to free the old string data, which will just be a garbage pointer).

Thank you all very much, the problem was a typo in the calculation of x.