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  1. /****************************************************************************
  2.  * cs50.c
  3.  *
  4.  * version 1.1.6
  5.  *
  6.  * Computer Science 50
  7.  * Glenn Holloway
  8.  * David J. Malan
  9.  *
  10.  * Definitions for the CS50 Library.
  11.  * Based on Eric Roberts' genlib.c and simpio.c.
  12.  *
  13.  * The latest version of this file can be found at
  14.  * http://w...content-available-to-author-only...0.net/pub/releases/cs50/cs50.c.
  15.  *
  16.  * To compile as a static library on your own system:
  17.  * % gcc -c -ggdb -std=c99 cs50.c -o cs50.o
  18.  * % ar rcs libcs50.a cs50.o
  19.  * % rm -f cs50.o
  20.  * % cp cs50.h /usr/local/include
  21.  * % cp libcs50.a /usr/local/lib
  22.  ***************************************************************************/
  23.  
  24. #include <stdio.h>
  25. #include <stdlib.h>
  26. #include <string.h>
  27.  
  28. #include "cs50.h"
  29.  
  30.  
  31. /*
  32.  * Default capacity of buffer for standard input.
  33.  */
  34.  
  35. #define CAPACITY 128
  36.  
  37.  
  38. /*
  39.  * Reads a line of text from standard input and returns the equivalent
  40.  * char; if text does not represent a char, user is prompted to retry.
  41.  * Leading and trailing whitespace is ignored.  If line can't be read,
  42.  * returns CHAR_MAX.
  43.  */
  44.  
  45. char
  46. GetChar(void)
  47. {
  48.     // try to get a char from user
  49.     while (true)
  50.     {
  51.         // get line of text, returning CHAR_MAX on failure
  52.         string line = GetString();
  53.         if (line == NULL)
  54.             return CHAR_MAX;
  55.  
  56.         // return a char if only a char (possibly with
  57.         // leading and/or trailing whitespace) was provided
  58.         char c1, c2;
  59.         if (sscanf(line, " %c %c", &c1, &c2) == 1)
  60.         {
  61.             free(line);
  62.             return c1;
  63.         }
  64.         else
  65.         {
  66.             free(line);
  67.             printf("Retry: ");
  68.         }
  69.     }
  70. }
  71.  
  72.  
  73. /*
  74.  * Reads a line of text from standard input and returns the equivalent
  75.  * double as precisely as possible; if text does not represent a
  76.  * double, user is prompted to retry.  Leading and trailing whitespace
  77.  * is ignored.  For simplicity, overflow and underflow are not detected.
  78.  * If line can't be read, returns DBL_MAX.
  79.  */
  80.  
  81. double
  82. GetDouble(void)
  83. {
  84.     // try to get a double from user
  85.     while (true)
  86.     {
  87.         // get line of text, returning DBL_MAX on failure
  88.         string line = GetString();
  89.         if (line == NULL)
  90.             return DBL_MAX;
  91.  
  92.         // return a double if only a double (possibly with
  93.         // leading and/or trailing whitespace) was provided
  94.         double d; char c;
  95.         if (sscanf(line, " %lf %c", &d, &c) == 1)
  96.         {
  97.             free(line);
  98.             return d;
  99.         }
  100.         else
  101.         {
  102.             free(line);
  103.             printf("Retry: ");
  104.         }
  105.     }
  106. }
  107.  
  108.  
  109. /*
  110.  * Reads a line of text from standard input and returns the equivalent
  111.  * float as precisely as possible; if text does not represent a float,
  112.  * user is prompted to retry.  Leading and trailing whitespace is ignored.
  113.  * For simplicity, overflow and underflow are not detected.  If line can't
  114.  * be read, returns FLT_MAX.
  115.  */
  116.  
  117. float
  118. GetFloat(void)
  119. {
  120.     // try to get a float from user
  121.     while (true)
  122.     {
  123.         // get line of text, returning FLT_MAX on failure
  124.         string line = GetString();
  125.         if (line == NULL)
  126.             return FLT_MAX;
  127.  
  128.         // return a float if only a float (possibly with
  129.         // leading and/or trailing whitespace) was provided
  130.         char c; float f;
  131.         if (sscanf(line, " %f %c", &f, &c) == 1)
  132.         {
  133.             free(line);
  134.             return f;
  135.         }
  136.         else
  137.         {
  138.             free(line);
  139.             printf("Retry: ");
  140.         }
  141.     }
  142. }
  143.  
  144.  
  145. /*
  146.  * Reads a line of text from standard input and returns it as an
  147.  * int in the range of [-2^31 + 1, 2^31 - 2], if possible; if text
  148.  * does not represent such an int, user is prompted to retry.  Leading
  149.  * and trailing whitespace is ignored.  For simplicity, overflow is not
  150.  * detected.  If line can't be read, returns INT_MAX.
  151.  */
  152.  
  153. int
  154. GetInt(void)
  155. {
  156.     // try to get an int from user
  157.     while (true)
  158.     {
  159.         // get line of text, returning INT_MAX on failure
  160.         string line = GetString();
  161.         if (line == NULL)
  162.             return INT_MAX;
  163.  
  164.         // return an int if only an int (possibly with
  165.         // leading and/or trailing whitespace) was provided
  166.         int n; char c;
  167.         if (sscanf(line, " %d %c", &n, &c) == 1)
  168.         {
  169.             free(line);
  170.             return n;
  171.         }
  172.         else
  173.         {
  174.             free(line);
  175.             printf("Retry: ");
  176.         }
  177.     }
  178. }
  179.  
  180.  
  181. /*
  182.  * Reads a line of text from standard input and returns an equivalent
  183.  * long long in the range [-2^63 + 1, 2^63 - 2], if possible; if text
  184.  * does not represent such a long long, user is prompted to retry.
  185.  * Leading and trailing whitespace is ignored.  For simplicity, overflow
  186.  * is not detected.  If line can't be read, returns LLONG_MAX.
  187.  */
  188.  
  189. long long
  190. GetLongLong(void)
  191. {
  192.     // try to get a long long from user
  193.     while (true)
  194.     {
  195.         // get line of text, returning LLONG_MAX on failure
  196.         string line = GetString();
  197.         if (line == NULL)
  198.             return LLONG_MAX;
  199.  
  200.         // return a long long if only a long long (possibly with
  201.         // leading and/or trailing whitespace) was provided
  202.         long long n; char c;
  203.         if (sscanf(line, " %lld %c", &n, &c) == 1)
  204.         {
  205.             free(line);
  206.             return n;
  207.         }
  208.         else
  209.         {
  210.             free(line);
  211.             printf("Retry: ");
  212.         }
  213.     }
  214. }
  215.  
  216.  
  217. /*
  218.  * Reads a line of text from standard input and returns it as a string,
  219.  * sans trailing newline character.  (Ergo, if user inputs only "\n", 
  220.  * returns "" not NULL.)  Leading and trailing whitespace is not ignored.
  221.  * Returns NULL upon error or no input whatsoever (i.e., just EOF).
  222.  */
  223.  
  224. string
  225. GetString(void)
  226. {
  227.     // growable buffer for chars
  228.     string buffer = NULL;
  229.  
  230.     // capacity of buffer
  231.     unsigned int capacity = 0;
  232.  
  233.     // number of chars actually in buffer
  234.     unsigned int n = 0;
  235.  
  236.     // character read or EOF
  237.     int c;
  238.  
  239.     // iteratively get chars from standard input
  240.     while ((c = fgetc(stdin)) != '\n' && c != EOF)
  241.     {
  242.         // grow buffer if necessary
  243.         if (n + 1 > capacity)
  244.         {
  245.             // determine new capacity: start at CAPACITY then double
  246.             if (capacity == 0)
  247.                 capacity = CAPACITY;
  248.             else if (capacity <= (UINT_MAX / 2))
  249.                 capacity *= 2;
  250.             else
  251.             {
  252.                 free(buffer);
  253.                 return NULL;
  254.             }
  255.  
  256.             // extend buffer's capacity
  257.             string temp = realloc(buffer, capacity * sizeof(char));
  258.             if (temp == NULL)
  259.             {
  260.                 free(buffer);
  261.                 return NULL;
  262.             }
  263.             buffer = temp;
  264.         }
  265.  
  266.         // append current character to buffer
  267.         buffer[n++] = c;
  268.     }
  269.  
  270.     // return NULL if user provided no input
  271.     if (n == 0 && c == EOF)
  272.         return NULL;
  273.  
  274.     // minimize buffer
  275.     string minimal = malloc((n + 1) * sizeof(char));
  276.     strncpy(minimal, buffer, n);
  277.     free(buffer);
  278.  
  279.     // terminate string
  280.     minimal[n] = '\0';
  281.  
  282.     // return string
  283.     return minimal;
  284. }
  285.  
  286. #include <stdio.h>
  287.  
  288.  
  289. int main(void) {
  290. 	// your code goes here
  291. 	return 0;
  292. }
  293.  
Success #stdin #stdout 0.01s 5396KB
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https://ideone.com/lwi3Fd
language:
C (gcc 8.3)
created:
1 year ago
visibility:
public

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