6. Implement type checking

Ex. No: 6

Date:

6. Implement type checking

AIM
   To write a C program to implement type checking


ALGORITHM:

Step-1: Track the global scope type information (e.g. classes and their members)
Step-2: Determine the type of expressions recursively, i.e. bottom-up, passing the resulting types upwards.
Step-3: If type found correct, do the operation
Step-4: Type mismatches, semantic error will be notified Start

PROGRAM


#include<stdio.h>
 #include<string.h>
struct symTable
{
int type;
char var[10];
}sT[50];
int c = 0;
void sep(char a[])
{
int len = strlen(a);
int i,j=0;
char temp[50],tp[50];
for(i = 0; i < len;++i)
{
if(a[i] != 32)
tp[i] = a[i];
else
break;
}
tp[i] = '\0';
temp[0]='\0';
++i;

for(;i < len;++i)
{
if(a[i] != ',' && a[i] != 32 && a[i] != ';')
temp[j++] = a[i];
else
{
if(strcmp(tp,"int") == 0)
sT[c].type = 1;
else if(strcmp(tp,"float") == 0)
sT[c].type = 2;
strcpy(sT[c++].var,temp);
temp[0] = '\0';
j=0;
}
}
}
int check(char a[])
{
int len = strlen(a);
int i, j = 0,key = 0,k;
char temp[50];
for(i = 0;i < len;++i)
{
if(a[i] != 32 && a[i] != '+' && a[i] != '=' && a[i] != ';')
temp[j++] = a[i];
else
{
temp[j]='\0';
for(k = 0;k < c;++k)
{
if(strcmp(sT[k].var,temp) == 0)
{
if(key == 0)
key = sT[k].type;
else if(sT[k].type != key)
return 0;
}
}
j = 0;
}
}
return 1;
}
void main()
{
int N,ans,i;
char s[50];
printf("\n Enter the total lines of declaration\n");
scanf("%d",&N);
while(N--)
{
scanf(" %[^\n]",s);
sep(s);
}
printf("Enter the expression:\n");
scanf(" %[^\n]",s);
if(check(s))
printf("Correct\n");
else
printf("Semantic error\n");
}

OUTPUT:

 Enter the total lines of declaration
2
int a,b;
float e;
Enter the expression:
e=a+b;
Semantic error







RESULT:

Thus the above program is compiled and executed successfully and output is verified.