Simple finite state machine in C
I'm vaguely plotting a finite state machine -> C compiler (as toy code, not for a serious project - I know there are plenty already out there), so thought I'd write a sample one by hand to see how it should look. Here's the code for it.
This checks if stdin contains the phrase 'foo' or 'bar'
This checks if stdin contains the phrase 'foo' or 'bar'
1 2 #include <stdio.h> 3 4 main() 5 { 6 int c; 7 8 START: 9 switch(c = getchar()){ 10 case 'f' : goto F; 11 case 'b' : goto B; 12 case EOF : goto FAIL; 13 default: goto START; } 14 15 F: 16 switch(c = getchar()){ 17 case 'o' : goto FO; 18 case EOF : goto FAIL; 19 default : goto START;} 20 21 FO: 22 switch(c = getchar()){ 23 case 'o' : goto SUCCESS; 24 case EOF : goto FAIL; 25 default : goto START;} 26 27 B: 28 switch(c = getchar()){ 29 case 'a' : goto BA; 30 case EOF : goto FAIL; 31 default : goto START;} 32 33 BA: 34 switch(c = getchar()){ 35 case 'r' : goto SUCCESS; 36 case EOF : goto FAIL; 37 default : goto START;} 38 39 FAIL: 40 printf("Does not match.\n"); 41 return; 42 SUCCESS: 43 printf("Matches.\n"); 44 return; 45 } 46 47
