数据文件的问题 [英] problem with Data Files
问题描述
大家好，
当我尝试从文件中输入一个字符时会发生什么
已完成，换句话说''c'包含什么'在执行以下代码中的最后一个
语句之后：
FILE * file = fopen（" FILE1.c"，" r"）;
char c;
while（（c = fgetc（file））！= EOF）;
c = fgetc（file）;
//现在c的值是多少?????????????????
谢谢，
Alice
hi all,
What will happen when I tries to input a character from a file
which is finished, in other words what will ''c'' contains after the last
statement in the following code is executed :
FILE * file =fopen("FILE1.c","r");
char c;
while((c=fgetc(file)) != EOF);
c=fgetc(file);
// what is value of c now???????????????????
Thanks,
Alice
推荐答案
2005年1月18日星期二09:38:54 -0800，alice写道：
On Tue, 18 Jan 2005 09:38:54 -0800, alice wrote:
大家好，
当我尝试从文件中输入一个完成的字符时会发生什么，换句话说，在最后一个文件中包含什么''c''执行以下代码中的语句：
FILE * file = fopen（" FILE1.c"，" r"）;
char c;
while（ （c = fgetc（file））！= EOF）;
这是不正确的，c需要定义为int。 fgetc（）返回int和
EOF不能保证可以表示为char。如果不是它不会与所有可能的char值区别开来。
c = fgetc（文件）;
//现在c的值是多少???????????????????谢谢，
hi all,
What will happen when I tries to input a character from a file
which is finished, in other words what will ''c'' contains after the last
statement in the following code is executed :
FILE * file =fopen("FILE1.c","r");
char c;
while((c=fgetc(file)) != EOF);
This is incorrect, c needs to be defined as int. fgetc() returns int and
EOF is not guaranteed to be representable as a char. If it is it won''t be
distinct from all possible char values.
c=fgetc(file);
// what is value of c now??????????????????? Thanks,
可能再次EOF，如果在此期间文件结束条件
被清除，可能还有其他内容。文件结束条件可能很粘，但它不是必须的b $ b。如果您想在
指示文件结束后再尝试进行文件I / O，则应该执行文件搜索操作，如果
合适，或者调用clearerr（ ）。你不应该只是尝试另外的阅读操作。
劳伦斯
Probably EOF again, maybe something else if the end-of-file condition
cleared in the meantime. End-of-file condition can be sticky but it
doesn''t have to be. If you want to attempt further file I/O after
end-of-file is indicated you should perform a file seek operation if that
is appropriate or else call clearerr(). You should not simply attempt
another read operation.
Lawrence
EOF（-1）
EOF (-1)
" bhanu" <去*********** @ hotmail.com>写道：
"bhanu" <go***********@hotmail.com> writes:
EOF（-1）
EOF通常为-1，但不保证该值。 EOF可以是任何
负'int''值。
-
int main（void）{char p [] =" ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuv wxyz。\
\ n"，* q =" kl BIcNBFr.NKEzjwCIxNJC" ;; int i = sizeof p / 2; char * strchr（）; int putchar（\
）; while（* q）{i + = strchr（p，* q ++） - p; if（i> =（int）sizeof p）i- = sizeof p-1; putchar（p [i ] \
）;}返回0;}
EOF is often -1 but that value is not guaranteed. EOF may be any
negative `int'' value.
--
int main(void){char p[]="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuv wxyz.\
\n",*q="kl BIcNBFr.NKEzjwCIxNJC";int i=sizeof p/2;char *strchr();int putchar(\
);while(*q){i+=strchr(p,*q++)-p;if(i>=(int)sizeof p)i-=sizeof p-1;putchar(p[i]\
);}return 0;}
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