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分享while（ch=getchar()!='#'）与while（（ch=getchar()）!='#'）有什么区别
下面这两个程序运行结果不一样 为什么？
#include <stdio.h>
void main()
{
int line,space,other;
char ch;
line=0;
space=0;
other=0;
while(ch=getchar()!='#')
{
if(ch==' ')
space++;
else
if(ch=='\n') line++;
else
other++;
}
printf("%d %d %d\n",space,line,other);
}
#include <stdio.h>
void main()
{
int line,space,other;
char ch;
line=0;
space=0;
other=0;
while(（ch=getchar()）!='#')
{
if(ch==' ')
space++;
else
if(ch=='\n') line++;
else
other++;
}
printf("%d %d %d\n",space,line,other);
}
#include <stdio.h>
void main()
{
int line,space,other;
char ch;
line=0;
space=0;
other=0;
while(ch=getchar()!='#')
{
if(ch==' ')
space++;
else
if(ch=='\n') line++;
else
other++;
}
printf("%d %d %d\n",space,line,other);
}
#include <stdio.h>
void main()
{
int line,space,other;
char ch;
line=0;
space=0;
other=0;
while(（ch=getchar()）!='#')
{
if(ch==' ')
space++;
else
if(ch=='\n') line++;
else
other++;
}
printf("%d %d %d\n",space,line,other);
}
...全文
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vv587 2016-06-15
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2楼正解。
优先级问题
xigua1102 2016-06-15
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运算优先级不要依靠设定的来，还是要靠自己加括号，易读，不易出错，不需要去记忆各种优先级
talkdream 2016-06-15
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倾向6楼的建议，多加（）好处多。
赵4老师 2016-06-12
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仅供参考：
//C++ Operators
// Operators specify an evaluation to be performed on one of the following:
// One operand (unary operator)
// Two operands (binary operator)
// Three operands (ternary operator)
// The C++ language includes all C operators and adds several new operators.
// Table 1.1 lists the operators available in Microsoft C++.
// Operators follow a strict precedence which defines the evaluation order of
//expressions containing these operators. Operators associate with either the
//expression on their left or the expression on their right; this is called
//“associativity.” Operators in the same group have equal precedence and are
//evaluated left to right in an expression unless explicitly forced by a pair of
//parentheses, ( ).
// Table 1.1 shows the precedence and associativity of C++ operators
// (from highest to lowest precedence).
//
//Table 1.1 C++ Operator Precedence and Associativity
// The highest precedence level is at the top of the table.
//+------------------+-----------------------------------------+---------------+
//| Operator | Name or Meaning | Associativity |
//+------------------+-----------------------------------------+---------------+
//| :: | Scope resolution | None |
//| :: | Global | None |
//| [ ] | Array subscript | Left to right |
//| ( ) | Function call | Left to right |
//| ( ) | Conversion | None |
//| . | Member selection (object) | Left to right |
//| -> | Member selection (pointer) | Left to right |
//| ++ | Postfix increment | None |
//| -- | Postfix decrement | None |
//| new | Allocate object | None |
//| delete | Deallocate object | None |
//| delete[ ] | Deallocate object | None |
//| ++ | Prefix increment | None |
//| -- | Prefix decrement | None |
//| * | Dereference | None |
//| & | Address-of | None |
//| + | Unary plus | None |
//| - | Arithmetic negation (unary) | None |
//| ! | Logical NOT | None |
//| ~ | Bitwise complement | None |
//| sizeof | Size of object | None |
//| sizeof ( ) | Size of type | None |
//| typeid( ) | type name | None |
//| (type) | Type cast (conversion) | Right to left |
//| const_cast | Type cast (conversion) | None |
//| dynamic_cast | Type cast (conversion) | None |
//| reinterpret_cast | Type cast (conversion) | None |
//| static_cast | Type cast (conversion) | None |
//| .* | Apply pointer to class member (objects) | Left to right |
//| ->* | Dereference pointer to class member | Left to right |
//| * | Multiplication | Left to right |
//| / | Division | Left to right |
//| % | Remainder (modulus) | Left to right |
//| + | Addition | Left to right |
//| - | Subtraction | Left to right |
//| << | Left shift | Left to right |
//| >> | Right shift | Left to right |
//| < | Less than | Left to right |
//| > | Greater than | Left to right |
//| <= | Less than or equal to | Left to right |
//| >= | Greater than or equal to | Left to right |
//| == | Equality | Left to right |
//| != | Inequality | Left to right |
//| & | Bitwise AND | Left to right |
//| ^ | Bitwise exclusive OR | Left to right |
//| | | Bitwise OR | Left to right |
//| && | Logical AND | Left to right |
//| || | Logical OR | Left to right |
//| e1?e2:e3 | Conditional | Right to left |
//| = | Assignment | Right to left |
//| *= | Multiplication assignment | Right to left |
//| /= | Division assignment | Right to left |
//| %= | Modulus assignment | Right to left |
//| += | Addition assignment | Right to left |
//| -= | Subtraction assignment | Right to left |
//| <<= | Left-shift assignment | Right to left |
//| >>= | Right-shift assignment | Right to left |
//| &= | Bitwise AND assignment | Right to left |
//| |= | Bitwise inclusive OR assignment | Right to left |
//| ^= | Bitwise exclusive OR assignment | Right to left |
//| , | Comma | Left to right |
//+------------------+-----------------------------------------+---------------+
ghx287524027 2016-06-08
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运算符优先级的问题，如果不清楚的话，建议多使用括号
xigua1102 2016-06-08
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楼上都给你说了，运算符优先级问题
所以写代码的时候，最好对于有多个运算符的增加括号明确运算顺序
不要交给默认的优先级
自己容易搞糊涂，别人读起来困难，出了问题也不好跟踪
paschen 2016-06-08
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优先级问题，前者ch等于 (getchar()!='#') 的计算结果（0或1），后者是ch = getchar()， 并判断ch是否等于'#'
0生而自由爱而无畏0 2016-06-08
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前面的是将获取的字符先判断是否为字符#，然后在赋值给ch。 而后面的是先将获取的字符赋值给ch，在进行判断是否为字符#。只是!=和=的优先级的问题，你回去好好看下
sds428 2016-06-08
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遇到疑惑，不清楚走向的，还是多加括号，这可是个好习惯哦，尤其在那一堆运算符大杂烩的地方
小灸舞 版主 2016-06-07
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!=的优先级大于=
所以你如果不加上括号的话while（ch=getchar()!='#'）
就会先计算getchar()!='#'，然后再将结果赋给ch
所以你如果不加上括号的话while（ch=getchar()!='#'）
就会先计算getchar()!='#'，然后再将结果赋给ch
