using static arrays

Discussion in 'C++' started by Jim, Jul 9, 2008.

  1. Jim

    Jim Guest

    I have a very simple object, freqoffset which I'm trying to use as
    members of a static array of in another class
    class freqoffset
    int set(double offset,double strength);
    double getOff() const{return offset;};
    double getStr() const{return strength;};
    double offset,strength;

    class nh3fitting
    static const int sn1=18;
    static const int sn2=21;
    static freqoffset s1[sn1];
    static freqoffset s2[sn2];
    nh3fitting(double cr, double cd, int n, double sd); //generates an
    array and populates it with x values
    static int loadArrays();

    int nh3fitting::loadArrays()
    s1[0].set( -1.56893, 0.0741);
    s1[1].set(-1.526658 , 0.1481);
    s1[2].set(-0.623335 , 0.0926);
    s1[3].set( -0.590375, 0.1667);
    s1[4].set(-0.581021, 0.0185);
    s1[5].set(-0.036389 , 0.0370);
    s1[6].set(-0.025453 , 0.0185);
    s1[7].set(-0.024583, 0.0333);
    s1[8].set(-0.015196, 0.3);
    s1[9].set(0.005941, 0.0185);
    s1[10].set(0.010463, 0.4667);
    s1[11].set(0.016835, 0.0926);
    s1[12].set(0.019832, 0.0333);
    s1[13].set(0.571708, 0.0926);
    s1[14].set(0.582719, 0.0185);
    s1[15].set(0.617689 , 0.1667);
    s1[16].set(1.53405, 0.0741);
    s1[17].set(1.545159, 0.1481);

    s2[0].set(-2.099033 ,0.0042 );
    s2[1].set(-2.058267 , 0.0377);
    s2[2].set( -2.053459, 0.0209);
    s2[3].set(-1.297087, 0.0372);
    s2[4].set(-1.296079,0.026 );
    s2[5].set(-1.255384, 0.0019);
    s2[6].set(-0.044498, 0.0209);
    s2[7].set(-0.041806, 0.0106);
    s2[8].set(-0.041456, 0.0116);
    s2[9].set(-0.001031, 0.1465);
    s2[10].set(0.000309, 0.4997);
    s2[11].set(0.001054, 0.2674);
    s2[12].set(0.039736, 0.0106);
    s2[13].set(0.042055, 0.0116);
    s2[14].set(0.046621 , 0.0209);
    s2[15].set(1.254559, 0.0019);
    s2[16].set(1.295363, 0.026);
    s2[17].set(1.296295, 0.0377);
    s2[18].set(2.053476, 0.0209);
    s2[19].set(2.058256, 0.0377);
    s2[20].set(2.099022, 0.0042);

    return 0;

    Unfortunately I get a linker error when trying to do this,
    g++ -I/usr/include/gsl/ -L/usr/lib/ -c nh3fit.cpp
    g++ -I/usr/include/gsl/ -L/usr/lib/ -lgsl -lgslcblas nh3fit.o -o
    nh3fit.o: In function `nh3fitting::loadArrays()':
    nh3fit.cpp:(.text+0xb7): undefined reference to `nh3fitting::s1'
    nh3fit.cpp:(.text+0xd9): undefined reference to `nh3fitting::s1'
    nh3fit.cpp:(.text+0xfb): undefined reference to `nh3fitting::s1'
    nh3fit.cpp:(.text+0x11d): undefined reference to `nh3fitting::s1'
    nh3fit.cpp:(.text+0x13f): undefined reference to `nh3fitting::s1'

    and so on for both s1 and s2. Does anyone have any suggestions?

    Thanks in advance,
    Jim, Jul 9, 2008
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  2. You declare two static arrays here, but you don't define
    ("instantiate") them anywhere. In other words, you are telling the
    compiler "these arrays exist somewhere" (which is one thing "static"
    does), however, you never actually create those arrays anywhere. Thus
    the linker cannot find them and complains.

    You have to put these somewhere:

    freqoffset nh3fitting::s1[nh3fitting::sn1];
    freqoffset nh3fitting::s2[nh3fitting::sn2];
    Juha Nieminen, Jul 9, 2008
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