Hi, I dont't understand why happens this thing in C:after compiling and running this little program: struct var{ char nume[32]; int*valori; }; main(){ FILE*p; struct var test,test2; test.valori=malloc(sizeof(int)); test.valori[0]=1; p=fopen("\\date.sta","w"); fwrite(&test,sizeof(struct var),1,p); fclose(p); p=fopen("\\date.sta","r"); fread(&test2,sizeof(struct var),1,p); printf("%d",test2.valori[0]); fclose(p); } the output is this: 1 (as expected), but if I split this code in 2 separate programs,like this Program 1: main(){ FILE*p; struct var test; test.valori=malloc(sizeof(int)); test.valori[0]=1; p=fopen("\\date.sta","w"); fwrite(&test,sizeof(struct var),1,p); fclose(p); } Program 2: main(){ FILE*p; struct var test; test.valori=malloc(sizeof(int)); p=fopen("\\date.sta","r"); fread(&test,sizeof(struct var),1,p); printf("%d",test.valori[0]); fclose(p); } the output of program 2 is, instead of 1, the unexpected 4239900. Can somebody explain this to me ? Thanks

eugensth, You're not allocating more memory for the *valori data member in the second var structure. What you're doing is writing the value of the _pointer_ *valori in the test structure (a memory address) to the file and then reading it into the test2 *valori data member. It "works" if you don't start a new program because the memory location contains the same data since the program never stopped. If you split it up, the memory location is trashed in between the two apps and is therefore an unexpected value. When you have pointers in structures, you can't just write the structure to the hard drive like, fwrite(&test,sizeof(struct var),1,p); Instead, you're going to have to write each data member seperately. Something like, fwrite(test.nume,sizeof(char)*32,1,p); fwrite(test.valori,sizeof(int),1,p); would work. Be sure to change the size of the data in the second fwrite to reflect how much memory you allocated! When reading, you can read the first part fine, but you'll have to allocate the *valori pointer before using it. fread(test2.nume,sizeof(char)*32,1,p); test2.valori=(int *)malloc(sizeof(int)); if(!test2.valori){exit(1);} fread(test2.valori,sizeof(int),1,p); Again, be sure to change the size of the data being read and allocated based on how much you wrote into the file. The 3rd line in the above code is something you need to do if you aren't doing it already. You can't assume malloc() will work and return valid memory. Check to see if the poiner equals NULL or 0. if(!ptr) is an easy way to do this (change ptr to the name of your pointer). Hope this helps. Things like this can be confusing, but don't let it discourage you. You've got to remember that when you're using a pointer, it's a dynamically created array. However, unlike normal arrays, the compiler doesn't know how much room you've got stored in that pointer (if any). Therefore, you cannot use a simple fwrite to write a structure with a pointer in it. You must take care of writing the structure, member by member, yourself. At least in C/C++. Good luck, Stephen "Live long and PROGRAM......or at least do _something_ with all that time...!"

Well, now I've fixed up the code and everything is OK.