c++ - null pointer is returned -

i have test defined this:

classname filehandle; classname1* data; //i want function define later  filehandle.getdata(data); //this null after call isn't in function calls                           //why isn't pointer defined method called? how fix? 

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the function calls looks this:

void classname::getdata(classname1* data) {     char * buf = "lots of data";             data = new classname1(buf, sizeof(buf)); //it's in there } 

i'm sure it's issue understanding of pointers , references. ideas i'm doing wrong here? why isn't value of data still defined when returns test?

i saw examples of pointers , function calls here i'm having trouble finding example this. this seems might similar too, i'm still confused.

pass pointer reference &:

void classname::getdata(classname1* &data2) 

for clarity renamed variables data1 , data2 can see different. when passing reference same, otherwise address stored in local pointer data2 destroyed after getdata function exits , null address stored in input data1 remains unaltered.

the call syntax remains same:

filehandle.getdata(data1);