[C] Da standard input a stringa

[noiseimpera]

se faccio in questo modo:

char* buff;
buff=(char*)malloc(sizeof(1000));
while((buff[i]=fgetc(stdin))!=EOF){
		i=i+1;		
}
buff[i]='\0';
buff=(char*) realloc((void*)buff,sizeof(i+2));

la realloc mi da problemi in memoria(invalid next size)