Unsigned char * data as return type of a function in c++ or c -

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• can turn unsigned char char , vice versa? 6 answers

i using visual studio 2010 clr(common language run time). want return unsigned char * compress function main function both unsigned char * , char * giving erro

"error 7 error c2440: '=' : cannot convert 'char *' 'unsigned char *' f:\4-2\thesis\project\database compression main\database compression 2\db_comp_main.cpp 21 "

unsigned char* compressor(char *data) {     unsigned char *compressed_string;     //with process had compressed string of data variable unsigned char* in variable compressed_string , printed here. want return here.     return compressed_string; } int main() {    unsigned char *main_data;    main_data=compressor("muhammad ashikuzzaman.student khulna university of engineering , technology bangladesh");// when click error error list cursor put here beside str visual studio.   printf("%s",main_data); } 

need return unsigned char * type data compressor function. please help.

change of data type (function argument *data or local variable *main_data) match type. try this

unsigned char *main_data; 

or....

simple type casting work make working anyway:

unsigned char* compressor(char *data) {     unsigned char *compressed_string;     compressed_string = (unsigned char*) data;     return compressed_string; } int main() {   char *main_data;   main_data=(char*) compressor("muhammad ashikuzzaman.student khulna university of engineering , technology bangladesh");   printf("%s",main_data); } 

or...

(changing char*)

there 3 char types: (plain) char, signed char , unsigned char. char 8-bit integer* (there's no dedicated "character type" in c language) , in sense, signed , unsigned char have useful meaning (generally equivalent uint8_t , int8_t). when used character in sense of text, use char (also referred plain char). typically signed char can implemented either way compiler. think using char* safe here.

working example (considering char * data type):

char* compressor(char *data) {     char *compressed_string;     compressed_string = "compressed";     // compressed_string = data;     return compressed_string; } int main() {    char *main_data;    main_data=compressor("muhammad ashikuzzaman.student khulna university of engineering , technology bangladesh");   printf("%s",main_data); } 

also, simplicity can use pointer pointer

void compressor(char **data) {     *data = "compressed"; // assuming compressed data smaller in length of main data, buffer overflow won't occur   }  int main() {     char *main_data = "muhammad ashikuzzaman.student khulna university of engineering , technology bangladesh";     compressor(&main_data);     printf("%s", main_data);     return 0; } 

edit

as asked alternative pass reference, there no way except pass reference regarding passing array function argument. because when write void func(char str[]) may think you're performing pass value. g++ compiler optimize statement void func(char &str[0]) avoid coping whole array function parameter. in scenario, passing reference.