编译成功了，但是程序运行不了，大神请看看

[qq_38448655]

#include <stdio.h>
int main()
{
double a;
double b;

scanf("%lf,%lf",&a, &b);

printf("result: %.3lf \n",a*b );

return 0;

}
程序运行却是这样的结果

[qq_38448655]

看来没人懂了。

[Cynhard]

小写的l后面不能加f，大写L后面才可以起加f，Lf表示 long double。 小写的l后面可以加d，ld表示long int。

[flying_music]

你输入的逗号是中文的

[Kiloveyousmile]

告诉我，你输入一个逗号要干嘛？有对应的读入变量？

[SK_AJIE]

scanf 是根据正则 进行读取输入的字符串的

[ToF君]

scanf错了

[赵4老师]

引用 8 楼 yshuise 的回复:

scanf是一个不好的函数，应用cin

乍看起来c++的cin、cout、ifstream、ofstream、istringstream、ostringstream在输入、输出上比c的scanf、printf、fscanf、fprintf、fread、fwrite、sscanf、sprintf简单，不用格式控制符！ 但是不用格式控制符，输入输出恰好是你期望的格式的时候好说；等到输入输出不是你期望的格式的时候，你就会觉得还是用格式控制符更方便、更靠谱。 摒弃cin、cout、ifstream、ofstream、istringstream、ostringstream！ 使用scanf、printf、fscanf、fprintf、fread、fwrite、sscanf、sprintf。

[赵4老师]

引用 6 楼 SK_AJIE 的回复:

scanf 是根据正则 进行读取输入的字符串的

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.

[yshuise]

scanf是一个不好的函数，应用cin

[亭台六七座]

图中标注位置换成英文逗号就可以了

[飞天神龟]

输出result之前把a,b都输出看看，是否有一个没有读入 请先学会调试

[ToF君]

[AlbertS]

输入的逗号是中文的，需要和scanf函数中的格式一致，要是逗号，都是英文逗号，要是空格都是空格

[easonlovejoyce]

能自己先单步调试下吗？