int i=0,j=0;
char operand[30];
char lbl[20],opr,num[20];
while(i<30)
lbl[i]=num[i]=operand[i++]=NULL;
cin>>operand;
for(i=0; operand[i]!='+' || operand[i]!='-'; i++)
lbl[i]=operand[i];
opr=operand[i++];
while(operand[i]!=NULL)
num[j++]=operand[i++];
..is there any mistake in this piece of code, my execution is getting stuck at
lbl[i]=operand[i];