C isnt running my switch statement - c

Question

I am having issues in C with a switch case
#include <stdio.h>
#include <strings.h>
void runprogram(void); // parses the input file
void display(int, int); // prints out the requested lines
void clearmemory(void); // clears the choice for input file
int traceflag = 0; //determines if the output should say everything
char memory[128]; //the file name for the input
void runprogram (void)
{
FILE *ifp; //file loaded
int total=0; //accumulator total
int temp3;
int a, b, c, d, numcnt, operand, opcode, CNNN;
char ch, ch2;
printf("Current File: %s\n",memory);
if(traceflag==0)
printf("Trace is off\n");
else
printf("Trace is on\n");
ifp = fopen(memory,"r"); //opens the file
char line [128];
char NNN[3];
char Cnnn[4];
char C[1];
a=0;
b=0;
c=0;
d=0;
numcnt=0;
while(fgets(line,sizeof line,ifp)!= NULL) // read a line from a file
{
while ((ch = line[b]) != '\0' )
{
if ( numcnt == 1 )
{
if (isdigit(ch))
{
ch2 = line [b + 1];
if ( isdigit( ch2 ))
{
for (a = 0; a < 4; a++ )
{
Cnnn [ a ] = ch;
b++;
ch = line [ b ];
}
for (a=0;a<4;a++)
{
if (a==0)
opcode=Cnnn[a];
else
NNN[a-1]=Cnnn[a];
}
numcnt++;
b=0;
a=0;
}
}
}
else if ( isdigit(ch))
{
ch2 = line [ b + 1 ];
if ( ch2 == ' ' )
numcnt++;
}
else
ch = line [ b ];
b++;
ch = line [ b ];
}
fgets( line, sizeof(line), ifp);
numcnt=0;
b=0;
d=0;
for (c = 0; c < 3; c++)
{
NNN [ c ] = Cnnn [ d + 1 ];
d++;
}
sscanf(NNN, "%d", &operand);
opcode=opcode/10;
b=0;
d=0;
/*if(traceflag==1)
{
printf("Full Line: %s\n",line); //print the file
printf("Opcode: %d\n", opcode);
}*/
printf("Opcode: %d Operand: %d\n", opcode, operand);
switch ( opcode )
{
case 0: //0 - Halt
printf("Run finished \n");
break;
case 1: //1 - Load: Copy memory nnn to accumulator
total=operand;
break;
case 2: //2 - Store: Copy accumulator to memory nnn
operand=total;
break;
case 3: //3 - Add memory nnn to accumulator
total=total+operand;
break;
case 4: //4 - Subtract memory nnn from accumulator
total=total-operand;
break;
case 5:
//int temp3; //temp to hold entered number
printf("Enter a number: ");
scanf(" %d",&temp3);
total=temp3;
break;
case 6:
printf("Accumulator: %d\n",total);
break;
case 7:
if(total==0)
opcode=operand/10;
break;
case 8: //8 ‐ Branch to nnn if the accumulator > 0
if(total>0)
opcode=operand/10;
break;
case 9: //9 – Branch to nnn
opcode=operand/10;
break;
default:
total=0;
break;
}
}
printf("Run finished \n");
fclose(ifp);
}`
The opcode is always an int, and it is the right int to run the switch.
yet for some reason it skips over the switch runs through all the lines and never outputs anything from within the switch case.
the file loaded is
0 Rd 5000
1 st n 2017
2 ld zero 1014
3 st sum 2016
4 L: ld n 1017
5 Add sum 3016
6 St sum 2016
7 Ld n 1017
8 Sub one 4015
9 St n 2017
10 Brgt L 8004
11 Ld sum 1016
12 Wr 6000
13 Stop 0000
14 Zero: 0 0000
15 One: 1 0001
16 Sum: 0 0000
17 N: 0 0000
Im not quite sure whats wrong with if and im not sure whats wrong i have tried many things and cant find anything online to help. Any input would be appreciated and if you cant compile and run the program i will give all the code. since the code is over 200 lines long i felt it would be inappropriate to post it all, yet if i must i will.

Answer 1

The problem is in the line opcode=Cnnn[a];
opcode is an int and Cnnn[a] is a char when you assign an int to a char it assigns the int value of the character according to the ASCII encoding. Example:
#include<stdio.h>
int main()
{
int a;
char b = '1';
a = b;
printf("%d", a);
return 0;
}
This prints out 49 because according to ascii the character '1' corresponds to 49
EDIT:
Im not sure if this is the "Correct" approach to solve your problem but since we notice that the int values we get are 48 more than the int value we want we can do opcode = (Cnnn[a] - 48);