c++ - Changing last 5 char of array -

i have program encrypts files, adds extension ".safe" end. end result "file.txt.safe"

when go decrypt file, user enters file name again: "file.txt.safe" saved char. want remove ".safe" , rename file original name.

i have tried following, nothing seems happen , there no errors.

decrypt (myfile); //decrypts myfile  char * tmp = myfile; char * newfile; newfile = strstr (tmp,".safe");  //search tmp ".safe" strncpy (newfile,"",5);   //replace .safe ""  rename (myfile, newfile); 

i'm sure i'm missing obvious, if approach doesn't work, i'm looking simple method.

edited add: (copied moderator poster's response k-ballo)

thanks everyone. took std::string approach , found work:

decrypt(myfile);  string str = myfile;  size_t pos = str.find(".safe");  str.replace(pos,5,"");  rename(myfile, str.c_str()); 

for want do, changing strncpy line work:

*newfile = '\0'; 

this still have problems if filename contains .safe (like in file.safest.txt.safe), or if not contain substring .safe @ all. better of searching end of array, , making sure find something.

this seems better approach (although in c++ better go std::string):

char* filename = ...; size_t filename_length = strlen( filename ); int safe_ext_pos = filename_length - 5; // 5 == length of ".safe" if( safe_ext_pos > 0 && strcmp( ".safe", filename + safe_ext_pos ) == 0 )     filename[ safe_ext_pos ] = '\0'; 

this std::string version of code:

std::string filename = ...; int safe_ext_pos = filename.length() - 5; // 5 == length of ".safe" if( safe_ext_pos > 0 && filename.compare( safe_ext_pos, 5, ".safe" ) == 0 )     filename.erase( safe_ext_pos );