c - Elementary XML parser -

i trying write elementary xml parser in c, without using non-standard libraries, able to:

• detect several different tags
• detect empty tag
• detect tag mismatch

the main problem have how differ which: beginning of tag, content , ending of tag.

my idea implement finite-state machine while reading file in order know reading.

please tell me ideas , correct me if pointed wrong direction.

edit: added chunk of code detects elements , content

char tmp, buff = -1; char *content = (char*) malloc(sizeof(char) * (size + 1)); int stage = -1; int = 0; while((tmp = fgetc(file)) != eof) {     if(tmp == '<') {         if(stage == 2 && buff != '>'){             printf("content: ");             printcont(content,i);         }         stage = 1;         buff = tmp;         = 0;         continue;     }else if(tmp == '/' && buff == '<') {         stage = 3;         buff = tmp;         = 0;         continue;     } else if(tmp == '>') {         if (stage == 1) {             printf("tag_start: ");         } else if (stage == 3) {             printf("tag_end: ");         } else if (stage == 2) {             printf("content: ");         }         buff = tmp;         printcont(content,i);//reads contnet         stage = 2;         = 0;         continue;     }     if(tmp != ' ' && tmp != '\n' && tmp != '\t') {//simple filter         content[i] = tmp;         buff = tmp;         i++;     } } 

i greatful if comment me on code above , tell me how improve it. far detects tags , content, needed in first place.

an fsm, itself, not enough. need 1 break text tokens specified xml spec, you'll need use other techniques recognize valid xml (or reject invalid xml).

you'll need write basic recursive descent parser take tokens , use them recognize valid xml.

this sounds basic enough assignment don't have worry 80% of what's in xml spec, make sure understand start tags , end tags. so, going non-trivial amount of work.