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另附cs50.h的代码
/****************************************************************************
* cs50.h
*
* version 1.1.6
*
* Computer Science 50
* Glenn Holloway
* David J. Malan
*
* Declarations for the CS50 Library.
* Based on Eric Roberts* genlib.h and simpio.h.
*
* The latest version of this file can be found at
* http://www.cs50.net/pub/releases/cs50/cs50.h.
*
* To compile as a static library on your own system:
* % gcc -c -ggdb -std=c99 cs50.c -o cs50.o
* % ar rcs libcs50.a cs50.o
* % rm -f cs50.o
* % cp cs50.h /usr/local/include
* % cp libcs50.a /usr/localb
***************************************************************************/
#ifndef _CS50_H
#define _CS50_H
#include <float.h>
#include <limits.h>
/*
* Borrow the standard library*s data type for Boolean variables whose
* values must be (true|false).
*/
#include <stdbool.h>
/*
* Our own data type for string variables.
*/
typedef char *string;
/*
* Reads a line of text from standard input and returns the equivalent
* char; if text does not represent a char, user is prompted to retry.
* Leading and trailing whitespace is ignored. If line can*t be read,
* returns CHAR_MAX.
*/
char
GetChar(void);
/*
* Reads a line of text from standard input and returns the equivalent
* double as precisely as possible; if text does not represent a
* double, user is prompted to retry. Leading and trailing whitespace
* is ignored. For simplicity, overflow and underflow are not detected.
* If line can*t be read, returns DBL_MAX.
*/
double
GetDouble(void);
/*
* Reads a line of text from standard input and returns the equivalent
* float as precisely as possible; if text does not represent a float,
* user is prompted to retry. Leading and trailing whitespace is ignored.
* For simplicity, overflow and underflow are not detected. If line can*t
* be read, returns FLT_MAX.
*/
float
GetFloat(void);
/*
* Reads a line of text from standard input and returns it as an
* int in the range of [-2^31 + 1, 2^31 - 2], if possible; if text
* does not represent such an int, user is prompted to retry. Leading
* and trailing whitespace is ignored. For simplicity, overflow is not
* detected. If line can*t be read, returns INT_MAX.
*/
int
GetInt(void);
/*
* Reads a line of text from standard input and returns an equivalent
* long long in the range [-2^63 + 1, 2^63 - 2], if possible; if text
* does not represent such a long long, user is prompted to retry.
* Leading and trailing whitespace is ignored. For simplicity, overflow
* is not detected. If line can*t be read, returns LLONG_MAX.
*/
long long
GetLongLong(void);
/*
* Reads a line of text from standard input and returns it as a string,
* sans trailing newline character. (Ergo, if user inputs only "\n",
* returns "" not NULL.) Leading and trailing whitespace is not ignored.
* Returns NULL upon error or no input whatsoever (i.e., just EOF).
*/
string GetString(void);
#endif

@zds68896578 @yxyy3604

另附cs50.c
/****************************************************************************
* CS50 Library 3.0
*
* https://manual.cs50.net/Library
*
* Glenn Holloway <holloway@eecs.harvard.edu>
* David J. Malan <malan@harvard.edu>
*
* Based on Eric Roberts* genlib.c and simpio.c.
*
* Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License
* http://creativecommons.org/licenses/by-nc-sa/3.0/
***************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "cs50.h"
/*
* Reads a line of text from standard input and returns the equivalent
* char; if text does not represent a char, user is prompted to retry.
* Leading and trailing whitespace is ignored. If line can*t be read,
* returns CHAR_MAX.
*/
char
GetChar(void)
{
// try to get a char from user
while (true)
{
// get line of text, returning CHAR_MAX on failure
string line = GetString();
if (line == NULL)
return CHAR_MAX;
// return a char if only a char (possibly with
// leading and/or trailing whitespace) was provided
char c1, c2;
if (sscanf(line, " %c %c", &c1, &c2) == 1)
{
free(line);
return c1;
}
else
{
free(line);
printf("Retry: ");
}
}
}
/*
* Reads a line of text from standard input and returns the equivalent
* double as precisely as possible; if text does not represent a
* double, user is prompted to retry. Leading and trailing whitespace
* is ignored. For simplicity, overflow and underflow are not detected.
* If line can*t be read, returns DBL_MAX.
*/
double
GetDouble(void)
{
// try to get a double from user
while (true)
{
// get line of text, returning DBL_MAX on failure
string line = GetString();
if (line == NULL)
return DBL_MAX;
// return a double if only a double (possibly with
// leading and/or trailing whitespace) was provided
double d; char c;
if (sscanf(line, " %lf %c", &d, &c) == 1)
{
free(line);
return d;
}
else
{
free(line);
printf("Retry: ");
}
}
}
/*
* Reads a line of text from standard input and returns the equivalent
* float as precisely as possible; if text does not represent a float,
* user is prompted to retry. Leading and trailing whitespace is ignored.
* For simplicity, overflow and underflow are not detected. If line can*t
* be read, returns FLT_MAX.
*/
float
GetFloat(void)
{
// try to get a float from user
while (true)
{
// get line of text, returning FLT_MAX on failure
string line = GetString();
if (line == NULL)
return FLT_MAX;
// return a float if only a float (possibly with
// leading and/or trailing whitespace) was provided
char c; float f;
if (sscanf(line, " %f %c", &f, &c) == 1)
{
free(line);
return f;
}
else
{
free(line);
printf("Retry: ");
}
}
}
/*
* Reads a line of text from standard input and returns it as an
* int in the range of [-2^31 + 1, 2^31 - 2], if possible; if text
* does not represent such an int, user is prompted to retry. Leading
* and trailing whitespace is ignored. For simplicity, overflow is not
* detected. If line can*t be read, returns INT_MAX.
*/
int
GetInt(void)
{
// try to get an int from user
while (true)
{
// get line of text, returning INT_MAX on failure
string line = GetString();
if (line == NULL)
return INT_MAX;
// return an int if only an int (possibly with
// leading and/or trailing whitespace) was provided
int n; char c;
if (sscanf(line, " %d %c", &n, &c) == 1)
{
free(line);
return n;
}
else
{
free(line);
printf("Retry: ");
}
}
}
/*
* Reads a line of text from standard input and returns an equivalent
* long long in the range [-2^63 + 1, 2^63 - 2], if possible; if text
* does not represent such a long long, user is prompted to retry.
* Leading and trailing whitespace is ignored. For simplicity, overflow
* is not detected. If line can*t be read, returns LLONG_MAX.
*/
long long
GetLongLong(void)
{
// try to get a long long from user
while (true)
{
// get line of text, returning LLONG_MAX on failure
string line = GetString();
if (line == NULL)
return LLONG_MAX;
// return a long long if only a long long (possibly with
// leading and/or trailing whitespace) was provided
long long n; char c;
if (sscanf(line, " %lld %c", &n, &c) == 1)
{
free(line);
return n;
}
else
{
free(line);
printf("Retry: ");
}
}
}
/*
* Reads a line of text from standard input and returns it as a
* string (char *), sans trailing newline character. (Ergo, if
* user inputs only "\n", returns "" not NULL.) Returns NULL
* upon error or no input whatsoever (i.e., just EOF). Leading
* and trailing whitespace is not ignored. Stores string on heap
* (via malloc); memory must be freed by caller to avoid leak.
*/
string
GetString(void)
{
// growable buffer for chars
string buffer = NULL;
// capacity of buffer
unsigned int capacity = 0;
// number of chars actually in buffer
unsigned int n = 0;
// character read or EOF
int c;
// iteratively get chars from standard input
while ((c = fgetc(stdin)) != *\n* && c != EOF)
{
// grow buffer if necessary
if (n + 1 > capacity)
{
// determine new capacity: start at 32 then double
if (capacity == 0)
capacity = 32;
else if (capacity <= (UINT_MAX / 2))
capacity *= 2;
else
{
free(buffer);
return NULL;
}
// extend buffer*s capacity
string temp = realloc(buffer, capacity * sizeof(char));
if (temp == NULL)
{
free(buffer);
return NULL;
}
buffer = temp;
}
// append current character to buffer
buffer[n++] = c;
}
// return NULL if user provided no input
if (n == 0 && c == EOF)
return NULL;
// minimize buffer
string minimal = malloc((n + 1) * sizeof(char));
strncpy(minimal, buffer, n);
free(buffer);
// terminate string
minimal[n] = *\0*;
// return string
return minimal;
}

@kcjby

现在是这么个情况@kcjby