user-0 提问: 一个从输入中读取double数据的问题

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user: user-0
content: 引用 3 楼 zhao4zhong1 的回复:fscanf_s(fp, "%s%s%s %c %c %d%lf",              person.Id, sizeof(person.Id),             person.Name, sizeof(person.Name),             person.Birth, sizeof(person.Birth),             &person.Sex, sizeof(person.Sex),             &person.Marriage, sizeof(person.Marriage),             &person.Height, sizeof(person.Height),             &person.Weight, sizeof(person.Weight)             );   Format Specification Fields: scanf and wscanf Functions A format specification has the following form:  % [width] [{h | l | I64 | L}]type  The format argument specifies the interpretation of the input and can contain one or more of the following:   White-space characters: blank (' '); tab ('\t'); or newline ('\n'). A white-space character causes scanf to read, but not store, all consecutive white-space characters in the input up to the next non–white-space character. One white-space character in the format matches any number (including 0) and combination of white-space characters in the input.   Non–white-space characters, except for the percent sign (%). A non–white-space character causes scanf to read, but not store, a matching non–white-space character. If the next character in stdin does not match, scanf terminates.   Format specifications, introduced by the percent sign (%). A format specification causes scanf to read and convert characters in the input into values of a specified type. The value is assigned to an argument in the argument list.  The format is read from left to right. Characters outside format specifications are expected to match the sequence of characters in stdin; the matching characters in stdin are scanned but not stored. If a character in stdin conflicts with the format specification, scanf terminates, and the character is left in stdin as if it had not been read.  When the first format specification is encountered, the value of the first input field is converted according to this specification and stored in the location that is specified by the first argument. The second format specification causes the second input field to be converted and stored in the second argument, and so on through the end of the format string.  An input field is defined as all characters up to the first white-space character (space, tab, or newline), or up to the first character that cannot be converted according to the format specification, or until the field width (if specified) is reached. If there are too many arguments for the given specifications, the extra arguments are evaluated but ignored. The results are unpredictable if there are not enough arguments for the format specification.  Each field of the format specification is a single character or a number signifying a particular format option. The type character, which appears after the last optional format field, determines whether the input field is interpreted as a character, a string, or a number.   The simplest format specification contains only the percent sign and a type character (for example, %s). If a percent sign (%) is followed by a character that has no meaning as a format-control character, that character and the following characters (up to the next percent sign) are treated as an ordinary sequence of characters, that is, a sequence of characters that must match the input. For example, to specify that a percent-sign character is to be input, use %%.  An asterisk (*) following the percent sign suppresses assignment of the next input field, which is interpreted as a field of the specified type. The field is scanned but not stored.// crt_sscanf_s.c // This program uses sscanf_s to read data items // from a string named tokenstring, then displays them.  #include <stdio.h> #include <stdlib.h>  int main( void ) {    char  tokenstring[] = "15 12 14...";    char  s[81];    char  c;    int   i;    float fp;     // Input various data from tokenstring:    // max 80 character string plus NULL terminator    sscanf_s( tokenstring, "%s", s, _countof(s) );    sscanf_s( tokenstring, "%c", &c, sizeof(char) );    sscanf_s( tokenstring, "%d", &i );    sscanf_s( tokenstring, "%f", &fp );     // Output the data read    printf_s( "String    = %s\n", s );    printf_s( "Character = %c\n", c );    printf_s( "Integer:  = %d\n", i );    printf_s( "Real:     = %f\n", fp ); }从输入中获取数值时不需要在可选参数中指明缓冲区大小。 The sscanf_s function reads data from buffer into the location given by each argument. The arguments after the format string specify pointers to variables with a type that corresponds to a type specifier in format. Unlike the less secure version sscanf, a buffer size parameter is required when using the type field characters c, C, s, S and [.  参见MSDN原文：https://msdn.microsoft.com/library/t6z7bya3(v=vs.110).aspx

user: user-1
content: fscanf_s(fp, "%s%s%s %c %c %d%lf",              person.Id, sizeof(person.Id),             person.Name, sizeof(person.Name),             person.Birth, sizeof(person.Birth),             &person.Sex, sizeof(person.Sex),             &person.Marriage, sizeof(person.Marriage),             &person.Height, sizeof(person.Height),             &person.Weight, sizeof(person.Weight)             );   Format Specification Fields: scanf and wscanf Functions A format specification has the following form:  % [width] [{h | l | I64 | L}]type  The format argument specifies the interpretation of the input and can contain one or more of the following:   White-space characters: blank (' '); tab ('\t'); or newline ('\n'). A white-space character causes scanf to read, but not store, all consecutive white-space characters in the input up to the next non–white-space character. One white-space character in the format matches any number (including 0) and combination of white-space characters in the input.   Non–white-space characters, except for the percent sign (%). A non–white-space character causes scanf to read, but not store, a matching non–white-space character. If the next character in stdin does not match, scanf terminates.   Format specifications, introduced by the percent sign (%). A format specification causes scanf to read and convert characters in the input into values of a specified type. The value is assigned to an argument in the argument list.  The format is read from left to right. Characters outside format specifications are expected to match the sequence of characters in stdin; the matching characters in stdin are scanned but not stored. If a character in stdin conflicts with the format specification, scanf terminates, and the character is left in stdin as if it had not been read.  When the first format specification is encountered, the value of the first input field is converted according to this specification and stored in the location that is specified by the first argument. The second format specification causes the second input field to be converted and stored in the second argument, and so on through the end of the format string.  An input field is defined as all characters up to the first white-space character (space, tab, or newline), or up to the first character that cannot be converted according to the format specification, or until the field width (if specified) is reached. If there are too many arguments for the given specifications, the extra arguments are evaluated but ignored. The results are unpredictable if there are not enough arguments for the format specification.  Each field of the format specification is a single character or a number signifying a particular format option. The type character, which appears after the last optional format field, determines whether the input field is interpreted as a character, a string, or a number.   The simplest format specification contains only the percent sign and a type character (for example, %s). If a percent sign (%) is followed by a character that has no meaning as a format-control character, that character and the following characters (up to the next percent sign) are treated as an ordinary sequence of characters, that is, a sequence of characters that must match the input. For example, to specify that a percent-sign character is to be input, use %%.  An asterisk (*) following the percent sign suppresses assignment of the next input field, which is interpreted as a field of the specified type. The field is scanned but not stored.

user: user-0
content: 引用 1 楼 zhao4zhong1 的回复://请今后要用 int c; scanf("%c",&c); //时，都改为 char s[2]; int c; scanf("%1s",s); c=s[0]; 老师啊，你这是啥意思呢？ 是不是说不管我读取什么类型的数据，都把它作为字符串去接受，然后在字符串的基础上再去做合法验证和类型转换？ 》》》》》》》》》》》》》》》》》》》》》》》》》 能不能就我的实际问题解惑一下呢？

user: user-1
content: //请今后要用 int c; scanf("%c",&c); //时，都改为 char s[2]; int c; scanf("%1s",s); c=s[0];