Question

C语言执行 cl.exe 时出错

#include<stdio.h>
#define PI 3.14
main()
{int r; float s,1;
r=2;
s=PI*r*r;
1=2*r*PI;
printf("s=%f 1=%f",s,1);
}
--------------------Configuration: Cpp1 - Win32 Debug--------------------
Compiling...
Cpp1.cpp
C:\Documents and Settings\Administrator\桌面\Cpp1.cpp(4) : error C2059: syntax error : 'constant'
C:\Documents and Settings\Administrator\桌面\Cpp1.cpp(6) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
C:\Documents and Settings\Administrator\桌面\Cpp1.cpp(7) : warning C4244: '=' : conversion from 'double' to 'const int', possible loss of data
C:\Documents and Settings\Administrator\桌面\Cpp1.cpp(7) : error C2106: '=' : left operand must be l-value
C:\Documents and Settings\Administrator\桌面\Cpp1.cpp(9) : warning C4508: 'main' : function should return a value; 'void' return type assumed
执行 cl.exe 时出错.
Cpp1.exe - 1 error(s), 0 warning(s)

Answer 1

#include<stdio.h>
#define PI 3.14
main()
{int r; float s,l;
 r=2;
 s=PI*r*r;
 l=2*r*PI;
 printf("s=%f 1=%f",s,l);
}

这是正确的。

int r; float s,1

你用1作为变量名称是错误的。变量名称是下划线，字母，数字组成，但是数字不能单独作为变量名称，所以导致你下面的等式也错误

1=2*r*PI;

输出的结果当然也无法输出，把1改成L就行了