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Difference between qico.dll and qico4.dll

  • Hi,

    I have problem displaying icons in my application which is built in release mode. I've looked through the forum posts and find that a lot suggested to put qico4.dll file. I'm using Qt5.2.1 (Windows 7) and I've only have qico.dll in my folder. Is there a difference between both files or it's just the naming?
    qico.dll has been put in the folder plugins/imageformats/qico.dll but i still can't see the icons during runtime.
    Any ideas? Or where to download qico4.dll?

  • Hi.

    First of recheck in plugins folder the two file extensions by right click ->property.
    the file qico4.dll you have posted is wrong it must be a static file(.lib).
    Yes there is a difference b/w qico.dll and qico4
    the former is an dynamic library(.dll) and later is a static library(.lib).
    the dynamic library in one that loads at run time.whereas a static library is whose purpose is at linking time/compile time.
    for more info you can see the detailed discussion on Qt forum.
    "find here":

    hope this helps.

  • Hi,

    Thanks for the explanation. However, I cannot find qico4.dll in any of the folders. Do you know where I might find it?

  • Lifetime Qt Champion


    IIRC, qico4 was for Qt 4, since your are using Qt 5 just use the qico.dll, well, copy it at the right place.

    Just one correction, on Windows lib files have two meanings: either it's a static library or an import library. The use is the same: you link against those, however the second is used when you are using shared libraries (aka dlls)

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