Compilare: user.c: In function ‘main’: user.c:20:43: warning: unused variable ‘columns’ [-Wunused-variable] char *p = NULL,*e,temp[2000],temp1[2000],columns[200][200]; ^ user.c: In function ‘get_column’: user.c:105:30: warning: unused variable ‘p’ [-Wunused-variable] char line[2000],rand[2000],*p; ^ user.c: In function ‘main’: user.c:32:7: warning: ignoring return value of ‘fread’, declared with attribute warn_unused_result [-Wunused-result] fread(p,1,size,file_json); ^ user.c: In function ‘get_column’: user.c:111:7: warning: ignoring return value of ‘fread’, declared with attribute warn_unused_result [-Wunused-result] fread(line,1,2000,file_json); ^