// ([0-9]|(~!@#$%^&*-+=\/)|[a-z])*[a-z]+([0-9]|(~!@#$%^&*-+=\/)|[a-z])
int read_symbol(FILE *in, struct value *val)
{
char c;
const char valid_chars[] = "~!@#$%^&*-+=/\\";
unsigned int i, non_numerical_seen = 0;
for (i = 0; i < MAX_SYMBOL_SIZE; i++) {
c = fgetc(in);
if (isdelim(c)) {
break;
} else if (!(isalnum(c) || strchr(valid_chars, c))) {
val->symbol[i+1] = 0;
ungets(val->symbol, in);
return READ_INVALID_CHAR;
} else if (!isdigit(c) && !non_numerical_seen) {
non_numerical_seen = 1;
}
val->symbol[i] = c;
}
val->symbol[i] = 0;
if (!val->symbol[0] || !non_numerical_seen) {
ungets(val->symbol, in);
return READ_FAIL;
} else {
val->type = SYMBOL;
return READ_SUCCESS;
}
}
/* reverse Polish calculator */
main()
{
char s[] = "string to push onto input\n";
ungets(s);
printf("%s", s);
}
int main(int argc, char *argv[])
{
double op2;
char s[MAXOP];
while(--argc > 0){
ungets(" ");
ungets(*++argv);
switch(getop(s)){
case NUMBER:
push(atof(s));
break;
case '+':
push(pop() + pop());
break;
case '*':
push(pop() * pop());
break;
case '-':
op2 = pop();
push(pop() - op2);
break;
case '/':
op2 = pop();
if(op2 != 0.0)
push(pop() / op2);
else
printf("error: zero divisor\n");
break;
case '%':
op2 = pop();
if(op2 != 0.0)
push(fmod(pop(), op2));
else
printf("error: zero divisor\n");
break;
case '\n':
printf("\t%.8g\n", pop());
break;
default:
printf("error: unknown command %s\n", s);
argc = 1;
break;
}
}
printf("\t%.8g\n", pop());
return 0;
}
int main()
{
int c;
ungets("hello, world\n");
while ((c = getch()) != EOF)
putchar(c);
return 0;
}
int main() {
/* Example usage */
char c;
ungets("hello");
while ((c = getch()) != 'o')
putchar(c);
putchar(c);
return 0;
}
/*
* To better cope with complexity and to reduce the load on the preprocessor
* and the compiler, C programs exploit modularity, a software design technique
* that revolves on organizing code on independent, interchangeable modules
* each containing just one specific functionality out of all those provided by
* a larger program.
* One of the key concepts of modularity is that each module should 'know', or
* contain, only the bare minimum needed to perform its functionality.
* As such the ungets(s) function of this exercise, should just use ungetch,
* without 'knowing' details about its implementation, but only its interface.
*/
int main(void)
{
char s[MAXLINE];
/* read an input line and push it back onto the s string */
ungets(s);
printf("%s", s);
return 0;
}
int main()
{
char *s = "hello, world. this is a test.";
int c;
ungets(s);
while ((c = getch()) != EOF) // 通过 getch() 从 buf 中取字符到，并且逐个输出字符
putchar(c);
return 0;
}
int main(int argc, char *argv[]) {
char operator[MAXOP] = ""; // Operator
double operand; // Temporary operand
// Start the REPL (read, evaluate, and print loop)
while (--argc > 0) {
ungets(" "); // Push end of argument
ungets(*++argv); // Push an argument
switch(getop(operator)) {
case NUMBER:
dapush(atof(operator));
break;
case '+':
dapush(dapop() + dapop());
break;
case '-':
operand = dapop();
dapush(dapop() - operand);
break;
case '*':
dapush(dapop() * dapop());
break;
case '/':
operand = dapop();
dapush(dapop() / operand);
break;
default:
printf("Error: Unknown command '%s'\n", operator);
argc = 1;
break;
} // switch
} // while
printf("%.8g\n", dapop());
return 0;
}
int main(void)
{
int c;
ungets("String to test : ) \n");
while (bufp > 0) {
c = getch();
putchar(c);
}
return 0;
}
void getch
int main()
{
int c;
char *string="pushing characters back to its input";
ungets(string);
while((c=getch()) != EOF)
putchar(c);
return 0;
}
int main()
{
char s[MAXOP];
getop(s);
printf("s=%s\n", s);
ungets(s);
getop(s);
printf("s=%s\n", s);
getop(s);
printf("s=%s\n", s);
return 0;
}
main(void)
{
char c;
char ms[] = "Hello this is the test input.\n";
ungets(ms);
while((c = getch()) != '\n'){
putchar(c);
}
putchar('\n');
return 0;
}
int main(int argc, char **argv)
{
char s[MAXOP];
double op2;
while (--argc > 0) {
ungets(" ");
ungets(*++argv);
switch (getop(s)) {
case NUMBER:
push(atof(s));
break;
case '+':
case '*':
push(pop() + pop());
break;
case '-':
op2 = pop();
push(pop() - op2);
break;
case '/':
op2 = pop();
if (op2 == 0) {
fprintf(stderr, "error: zero divisor\n");
return -1;
}
push(pop() / op2);
break;
default:
fprintf(stderr, "error: unknown command %s\n", s);
argc = 1; /* next step is to jump out of while loop */
break;
}
}
printf("\t%.8g\n", pop()); /* print the result */
return 0;
}
/* standard input/output functions */
void ungets (char c[]);
int getch(void);
int ungetch(int); /* tare smekeră funcţia asta :
face push la o valoare intr-un buffer
pe care il imparte cu getch
*/
int main(void)
{
int i = 0;
char s[MAXOP + 1] = "ceva plus \0 ceva";
ungets(s);
printf("\n Your string containing EOF is");
while(buf[i] > 0)
printf("%c", buf[i++]);
return 0;
}
int main(int argc, char const *argv[])
{
char s[] = "Write a routine ungets(s) that will push back an entire string onto the input.";
char c;
ungets(s);
while((c = getc()) != EOF)
{
putchar(c);
}
return 0;
}
int read_string(FILE *in, struct value *val)
{
char c;
unsigned int i;
if ((c = fgetc(in)) != '\"') {
ungetc(c, in);
return READ_FAIL;
}
for (i = 0; (c = fgetc(in)) != '\"'; i++) {
if (EOF == c) {
val->string.arr[i] = 0;
ungets(val->string.arr, in);
return READ_MISMATCH_DELIM;
} else if ('\\' == c) {
c = fgetc(in);
if ('n' == tolower(c)) {
val->string.arr[i] = '\n';
} else if ('t' == tolower(c)) {
val->string.arr[i] = '\t';
} else if ('\"' == c) {
val->string.arr[i] = '\"';
} else {
val->string.arr[i] = 0;
ungets(val->string.arr, in);
return READ_INVALID_CHAR;
}
} else {
val->string.arr[i] = c;
}
}
val->type = STRING;
val->string.len = i;
return READ_SUCCESS;
}
main()
{
char s[100];
int c,i;
i=0;
while((c=getchar())!='q')
{
s[i++]=c;
}
ungetch(c);
printf("%c\n",getch());
ungets("98");
printf("%c\n",getch());
printf("%c\n",getch());
return 0;
}
main()
{
char w[MAXWORD];
struct nlist *p;
while (getword(w, MAXWORD) != EOF)
if (strcmp(w, "//") == 0)
getdef();
else if (!isalpha(w[0]))
printf("%s", w);
else if ((p = lookup(w)) == NULL)
printf("%s", w);
else
ungets(p->defn);
return 0;
}
// getlinef: get line with delimeter, and then the rest until '\n'
int getlinef(char ln[], char d[], int lim) {
int i, k, c, j;
char rest[lim];
for (i=k=0; i<lim && d[k] != '\0'; ++i) {
ln[i] = (c=getch());
if (c == d[k]) ++k;
else k = 0;
}
i -= k;
ln[i] = '\0';
for (j=0; j<lim && (c=getch()) != EOF && c != '\n'; ++j,++i)
rest[j] = c;
rest[j] = '\0';
ungets(rest);
return i;
}
int main(void) {
char buffer[BUFFER_SIZE] = { 0 };
char c = 0;
char d = 0;
while (1)
{
fgets(buffer, BUFFER_SIZE, stdin);
printf("%s\n", buffer);
ungets(buffer, stdin);
}
getchar();
return 0;
}
int read_character(FILE *in, struct value *val)
{
char c, special_char;
char buf[BUF_LEN] = {0};
char special_str[BUF_LEN] = {0};
unsigned int special_len, i;
if ((c = fgetc(in)) != '#') {
ungetc(c, in);
return READ_FAIL;
}
if ((c = fgetc(in)) != '\\') {
ungetc(c, in);
return READ_FAIL;
}
c = fgetc(in);
if (tolower(c) == 'n') {
special_char = '\n';
strcpy(special_str, "newline");
} else if (tolower(c) == 't') {
special_char = '\t';
strcpy(special_str, "tab");
} else if (tolower(c) == 's') {
special_char = ' ';
strcpy(special_str, "space");
}
if (special_str[0]) {
special_len = strlen(special_str);
for (i = 1; i < special_len; i++) {
buf[i-1] = c = fgetc(in);
if (tolower(c) != special_str[i]) {
ungets(buf, in);
return READ_INVALID_CHAR;
}
}
val->character = special_char;
} else {
val->character = c;
}
return READ_SUCCESS;
}
void ParseParamList(char *desc) {
int type;
char token[kMaxToken];
do {
ParseParamDecl(desc);
type = GetToken(token);
if (type == ',') {
strcat(desc, ",");
} else {
break;
}
} while (1);
// out of param list
ungets(token);
}
int main(void) {
printf("Write a routine ungets(s) that will push back an entire string onto the input.\n"
"Should ungets know about buf and bufp, or should it just use ungetch?\n");
printf("\nungets(s) should know about buf and bufp, since it can use that to determine if\n"
"the line to be placed in buf has enough space ready for it.\n");
printf("Please enter line of text: ");
ungets("This pre-ungotten string should appear first. ");
char c;
int i = 0;
while ((c = getch()) != '\n' && c != EOF) {
outString[i++] = c;
}
outString[i++] = '\0';
printf("\nPrinting received input from getch(): %s\n", outString);
return EXIT_SUCCESS;
}
/* (+|-|\0)[0-9]*.[0-9]+ */
int read_flonum(FILE *in, struct value *val)
{
char c;
char buf[BUF_LEN] = {0};
unsigned int i = 0, neg = 0, decimal_seen = 0;
c = fgetc(in);
if ('-' == c) {
neg = 1;
} else if (isdigit(c)) {
buf[i++] = c;
} else if ('.' == c) {
decimal_seen = 1;
buf[i++] = '0';
buf[i++] = '.';
} else if ((EOF == c) || (c != '+')) {
ungetc(c, in);
return READ_FAIL;
}
while (i < BUF_LEN) {
c = fgetc(in);
if ('.' == c)
decimal_seen = 1;
else if (!isdigit(c))
break;
buf[i] = c;
i++;
}
if (decimal_seen) {
val->flonum = atof(buf) * (neg ? -1 : 1);
val->type = FLONUM;
return READ_SUCCESS;
} else {
ungets(buf, in);
return READ_FAIL;
}
}
main()
{
int ch,i;
char s[100];
for(i=0;i<100;i++)
s[i]='\0';
i=0;
printf("\nEnter the string : ");
while((ch=getch())!=EOF && ch!='\n')
s[i++]=ch;
s[i]=0;
printf("\nString is %s",s);
ungets(s);
printf("\nAfter ungets %s",s);
i=0;
while((ch=getch())!=EOF && ch!='\n' && ch!='\0')
s[i++]=ch;
printf("\nAfter using ungets and the getch");
printf(" :%s\n",s);
}
/* (+|-|/0)[0-9]+ where /0 is a null token */
int read_fixnum(FILE *in, struct value *val)
{
char c;
char buf[BUF_LEN] = {0};
unsigned int i = 0, neg = 0;
c = fgetc(in);
if ('-' == c) {
neg = 1;
} else if (isdigit(c)) {
buf[i++] = c;
} else if ((EOF == c) || (c != '+')) {
ungetc(c, in);
return READ_FAIL;
}
while ((EOF != (c = fgetc(in))) && (i < BUF_LEN)) {
if (isdigit(c)) {
buf[i] = c;
} else if (isdelim(c)) {
ungetc(c, in);
break;
} else {
ungets(buf, in);
return READ_INVALID_CHAR;
}
i++;
}
if (buf[0] != 0) {
val->type = FIXNUM;
val->fixnum = atoi(buf) * (neg ? -1 : 1);
return READ_SUCCESS;
} else {
return READ_FAIL;
}
}
/* калькулятор с обратной польской записью */
int main(void)
{
int type;
double op1, op2;
char s[MAXOP];
for (int i = 0; i < CALPHABET; i++)
var[i].isInit = false;
while ((type = getop (s)) != EOF) {
switch (type) {
case NUMBER:
push (atof (s));
break;
case OPERAT:
// определить операцию
if (strequ(s, "sin", 3)) {
push( sin( pop() ) );
break;
} else if (strequ(s, "exp", 3)) {
push( exp( pop() ) );
break;
} else if (strequ(s, "pow", 3)) {
push( pow(pop(), pop()));
break;
}else if (strequ(s, "ungets", 6)) {
if (!fungets) {
ungets(s);
} else {
printf("Данные были возвращены в стандартный поток в\\в\n");
}
fungets = !fungets;
break;
}
printf("ошибка: неизвестная операция %s\n", s);
break;
case VARIABLE:
printf("добавлена переменная: ");
putchar(lastVar.name);
printf("=%.8g\n", lastVar.value);
break;
case '!': // Печатаем верхний элемент стека
printf("\ttop> %.8g\n", top());
break;
case '@': // Дублируем верхний элемент стека
clonetop();
break;
case '#': // Меняем местами два верхних элемента стека
xchg();
break;
case '$': // Очищаем стек
clear();
break;
case '%':
op2 = pop();
if (op2 != 0.0) {
op1 = pop();
push( op1 - op2 * (int)(op1 / op2) );
}
else
printf("ошибка: деление на нуль\n");
break;
case '+':
push (pop() + pop());
break;
case '*':
push (pop() * pop());
break;
case '-':
op2 = pop();
push (pop() - op2);
break;
case '/' :
op2 = pop();
if (op2 != 0.0)
push (pop() / op2);
else
printf("ошибка: деление на нуль\n");
break;
case '\n' :
printf("\t%.8g\n", pop());
break;
default:
printf("ошибка: неизвестная операция %s\n", s);
break;
}
}
return 0;
}
int main(int argc, char *argv[])
{
char word[MAXWORD];
if (argc != 2) {
printf("please enter the file name!\n");
return -1;
}
char *filename;
filename = argv[1];
FILE * fp;
if ((fp = fopen(filename, "r")) == NULL) {
printf("file is not exist!\n");
return -1;
}
char buffer[4096]; //how dirty it is..
int i = 0;
while (!feof(fp)) {
buffer[i++] = fgetc(fp);
}
/**
* that is the problem in func void ungets(char s[]) : int len = strlen(s);
* pay attention !!!!! the EOF will store in the buffer[i - 1], replace it with '\0'
*/
buffer[i - 1] = '\0';
fclose(fp);
ungetch(EOF); //it is necessary!
ungets(buffer);
int linenow = 1;
struct nlist *node;
struct nlist *node_parent;
while (getword(word, MAXWORD) != EOF) {
if ((word[0] == '\n')) {
linenow++;
}
if (word[1] == '\0' && !isalpha(word[0])) { //caocaocao == is not =
continue;
}
int hash_key = simple_hash(word, HASHSIZE);
node = hashtab[hash_key];
int is_node_exist = 0;
while (node != NULL) {
if (strcmp(node->name, word) == 0) {
is_node_exist = 1;
node->lines[node->linecount++] = linenow;
break;
}
node_parent = node;
node = node->next;
}
if (!is_node_exist) {
node = talloc();
node->next = NULL;
node->name = strdupp(word);
node->linecount = 0;
node->lines[node->linecount++] = linenow;
//the implement is dirty, how can I keep the consistency?
if (hashtab[hash_key] == NULL) {
hashtab[hash_key] = node;
} else {
node_parent->next = node;
}
}
}
for (i = 0; i < HASHSIZE; i++) {
node = hashtab[i];
while (node != NULL) {
printf("%s:", node->name);
int count = node->linecount;
while (count--) {
printf(" %d", node->lines[count]);
}
printf("\n");
node = node->next;
}
}
return 0;
}
/* Simple version of #define and #undef processor. */
int main() {
char word[kMaxWord];
char *name;
char defn[kMaxWord];
LinkNode *p;
int len = 0, i = 0;
enum ParserState state = kStart;
HashTable hash_table[kHashSize];
HashInit(hash_table, kHashSize);
memset(word, 0, kMaxWord);
memset(defn, 0, kMaxWord);
while (GetWord(word, kMaxWord) != EOF) {
switch (state) {
case kStart:
if (strcmp(word, "#define") == 0) {
state = kDefine;
} else if (strcmp(word, "#undef") == 0) {
state = kUnDef;
} else if (!isalpha(word[0])) {
printf("%s", word);
} else if ((p = HashSearch(hash_table, word)) == NULL) {
printf("%s", word);
} else {
ungets(p->defn);
}
break;
case kDefine:
if (isalpha(word[0])) {
name = strdup(word);
state = kName;
} else {
printf("Error: non-alpha name");
exit(1);
}
break;
case kName:
if (word[0] == '\n') {
printf("Error: incomplate define");
exit(1);
} else {
strcpy(defn, word);
len += strlen(word);
state = kDefn;
}
break;
case kDefn:
if (word[0] != '\n' && len < kMaxWord) {
strcat(defn, word);
len += strlen(word);
} else {
HashInsert(hash_table, name, defn);
state = kStart;
}
break;
case kUnDef:
if (isalpha(word[0])) {
HashDelete(hash_table, name);
state = kStart;
} else {
printf("Error: non-alpha name");
exit(1);
}
break;
}
}
return 0;
}
/* reverse Polish calculator
*
* all basic operators provided (+, *, -, /, %, sin, exp, pow) as well as some
* speciality commands:
*
* ` - clear stack
* # - duplicate top value of stack
* ? - print top value of stack
* ~ - swap top two values on stack
*
* variables (a-z) are also supported with the = operator
*
* the '!' character is a special variable which stores the most recently
* printed value
*
*/
int main() {
int type;
double op1, op2, last_printed;
char s[MAXOP];
while ((type = getop(s)) != EOF) {
switch (type) {
case NUMBER:
push(atof(s));
break;
case '+':
push(pop() + pop());
break;
case '*':
push(pop() * pop());
break;
case '-':
op2 = pop();
push(pop() - op2);
break;
case '/':
op2 = pop();
if (op2 != 0.0) {
push(pop() / op2);
} else {
printf("error: zero divisor\n");
}
break;
case '%':
op2 = pop();
op1 = pop();
if (op2 != 0.0) {
push(op1 - (int)(op1/op2) * op2);
} else {
printf("error: zero divisor\n");
}
break;
case SIN:
push(sin(pop()));
break;
case EXP:
push(exp(pop()));
break;
case POW:
op2 = pop();
push(pow(pop(), op2));
break;
case '`':
clear();
break;
case '#':
duplicate();
break;
case '?':
print();
break;
case '~':
swap();
break;
case VAR:
/* TODO: Add variable saving */
op2 = vars['z'-current_var];
push(op2);
break;
case '=':
op2 = pop();
vars['z'-current_var] = op2;
break;
case '!':
push(last_printed);
break;
case '\n':
last_printed = pop();
printf("\t%.8g\n", last_printed);
break;
default:
printf("error: unknown command %s\n", s);
break;
}
}
ungets("1 2 +\n");
printf("Current buffer: %s", buf);
return 0;
}