# K & R C Programs Exercise 7-5.

K and R C, Solution to Exercise 7-5:
K and R C Programs Exercises provides the solution to all the exercises in the C Programming Language (2nd Edition). You can learn and solve K&R C Programs Exercise.
Rewrite the postfix calculator of chapter 4 to use scanf and/or sscanf to do the input number conversion.

`/************************************************************ You can use all the programs on  www.c-program-example.com* for personal and learning purposes. For permissions to use the* programs for commercial purposes,* contact [email protected]* To find more C programs, do visit www.c-program-example.com* and browse!* *                      Happy Coding***********************************************************/#include<stdio.h>#include<math.h>       /*for atof()*/#define MAXTOP 100     /* max size of operand or operator  */#define NUMBER  '0'    /* SIGNAL THAT A NUMBER WAS FOUND   */#define MAXVAL 100int gettop(char []);void push(double);double pop(void);int sp = 0;          /* Next free stack position. */double val[MAXVAL];  //reverse Polish calulatorint main(void){ int type; double op2; 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("nError: Zero divissorn");   break;  case '%':   op2 = pop();   if(op2)    push(fmod(pop(), op2));   else    printf("nError: Division by zero!");   break;  case 'n':   printf("t%.8gn",pop());   break;   default:   printf("error: unknown command %sn", s);   break;  } } return 0;}/* Getop: get next operator or numeric operand. */int getop(char s[]){ int i = 0; int c; int rc; static char lastc[] = " "; sscanf(lastc,"%c", &c); lastc[0] = ' '; /* Skip whitespace */ while((s[0] = c ) == ' ' || c == 't')  if(scanf("%",&c) == EOF)   c = EOF; s[1] = ''; /* Not a number but may contain a unary minus. */ if(!isdigit(c) && c != '.' )  return c;                if(isdigit(c))  do{   rc = scanf("%c",&c);   if(!isdigit(s[++i] = c))    break;  }while(rc != EOF)   if(c == '.')    do{     rc = scanf("%c",&c);     if(!isdigit(s[++i] = c))      break;    }while(rc != EOF)     s[i] = ''; if(rc != EOF)  lastc[0] = c; return NUMBER;}/* push: push f onto stack. */void push(double f){ if(sp < MAXVAL)  val[sp++] = f; else  printf("nError: stack full can't push %gn", f);}/*pop: pop and return top value from stack.*/double pop(void){ if(sp > 0)  return val[--sp]; else {  printf("nError: stack emptyn");  return 0.0; }}`
`Read more c programsC BasicC StringsK and R C Programs Exercise`

You can easily select the code by double clicking on the code area above.

You can discuss these programs on our Facebook Page. Start a discussion right now,

our page!

(you can send this program to your friend using this button)

To browse more C Programs visit this link
(c) www.c-program-example.com

# K & R C Programs Exercise 7-4.

K and R C, Solution to Exercise 7-4:
K and R C Programs Exercises provides the solution to all the exercises in the C Programming Language (2nd Edition). You can learn and solve K&R C Programs Exercise.
Write a private version of scanf analogous to minprintf from the previous section.
minscanf is similar to minprintf. This function collects characters from the format string until it finds an alphabetic character after a %. That is the localfmt passsed to scanf along with the appropriate pointer.
The arguments to scanf are pointers: a pointer to a format string and a pointer to the variable that receives the value from scanf.Read more about C Programming Language .

`/************************************************************ You can use all the programs on  www.c-program-example.com* for personal and learning purposes. For permissions to use the* programs for commercial purposes,* contact [email protected]* To find more C programs, do visit www.c-program-example.com* and browse!* *                      Happy Coding***********************************************************/#include <stdarg.h>#include <stdio.h>#include <ctype.h>#define LOCALFMT 100/* minscanf:  minimal scanf with variable argument list */void minscanf(char *fmt, ...){ va_list ap; char *p, *sval; char localfmt[LOCALFMT]; int i,c; int *ival; double *dval; unsigned *uval; va_start(ap, fmt);    /* make ap point to the first unnamed arg */ for (p = fmt; *p; p++) {  if (*p != '%') {   localfmt[i++] = *p;   continue;  }  i = 0;  localfmt[i++] = '%';  while(*p(p+1) && !isalpha(*(p+1)))   localfmt[i++] = *++p;  localfmt[i++] = *(p+1);  localfmt[i] = '/0';  switch (*++p) {  case 'd':  case 'i':   ival = va_arg(ap, int *);   scanf(localfmt, ival);   break;  case 'u':  case 'o':  case 'x':  case 'X':  case 'f':   dval = va_arg(ap, double);   scanf(localfmt, dval);   break;  case 's':   sval = va_arg(ap, char *);   scanf(localfmt, sval);   break;  default:   scanf(localfmt);   break;  }  i = 0; } va_end(ap);}`
`Read more c programsC BasicC StringsK and R C Programs Exercise`

You can easily select the code by double clicking on the code area above.

You can discuss these programs on our Facebook Page. Start a discussion right now,

our page!

(you can send this program to your friend using this button)

To browse more C Programs visit this link
(c) www.c-program-example.com

# C Program to demonstrate sscanf statement.

C Program to demonstrate the ‘sscanf’ statement.
sscanf statement reads formatted data from the string, Different syntax of sscanf are:
A = sscanf(str, format)
A = sscanf(str, format, sizeA)
[A, count] = sscanf(…)
[A, count, errmsg] = sscanf(…)
[A, count, errmsg, nextindex] = sscanf(…).Read more about C Programming Language .

`/************************************************************ You can use all the programs on  www.c-program-example.com* for personal and learning purposes. For permissions to use the* programs for commercial purposes,* contact [email protected]* To find more C programs, do visit www.c-program-example.com* and browse!* *                      Happy Coding***********************************************************/#include <stdio.h>main(){ char Host[64]; char User[64]; char *Buff = "Jobname=job1 Hostname=arnamul User=leslim Time=11:15"; /*            <---------->          <-----> <---------> <-------->  *              |                      |         |           |  *              |           ------------         |           |  *              |           |   ------------------           V  *              |           |   |                       NULL  *              V           V   V                                    */ sscanf (Buff, "%*s Hostname=%s %s", Host, User); printf("Host is %sn", Host); printf("User is %sn", User); exit(0);}`
`Read more c programs `
`C BasicC StringsK and R C Programs Exercise`

You can easily select the code by double clicking on the code area above.