Compilare: user.cpp: In function ‘int substring(char*, char*)’: user.cpp:42: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:55: warning: format ‘%s’ expects type ‘char*’, but argument 3 has type ‘char (*)[101]’ user.cpp:53: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp:55: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result