C++ 错误：“(”标记之前的预期标识符

Question

int nn1,nn2;
for (int i=1;i<=m;i++) if (A[i]>minim) && (A[i]<maxim) nn1++;
for (int j=1;j<=n;j++) if (B[j]>minim) && (B[j]<maxim) nn2++;
if (nn1>nn2) cout<<"1";
if (nn1<nn2) cout<<"2";
if (nn1=nn2) cout<<"0";

return 0;
}

can anybody give me a suggestion please why the compiler shows the error?

Answer 1

In these if statements there are absent external parentheses

for (int i=1;i<=m;i++) if (A[i]>minim) && (A[i]<maxim) nn1++;
for (int j=1;j<=n;j++) if (B[j]>minim) && (B[j]<maxim) nn2++;

I think that there should be

for (int i=1;i<=m;i++) if ( (A[i]>minim) && (A[i]<maxim) ) nn1++;
for (int j=1;j<=n;j++) if ( (B[j]>minim) && (B[j]<maxim) ) nn2++;

And the loops look suspeciously. Take into account that array indices start from 0. So for example if you have an array of size N then the valid range of indices is [0, N-1]

And you forgot to initialize nn1 and nn2 .

It seems that you mean the following

int nn1 = 0, nn2 = 0;

for ( int i = 0; i < m; i++ ) 
{
    if ( ( A[i] > minim ) && ( A[i] < maxim ) ) nn1++;
}

for ( int i = 0; i < n; i++ ) 
{
    if ( ( B[i] > minim ) && ( B[i] < maxim ) ) nn2++;
}

if ( nn1 > nn2 ) cout << "1";
else if ( nn1 < nn2 ) cout << "2";
else cout << "0";

Answer 2

Fix the brackets in if condition. Something like if (condition1 && condition2). I also suggest using curly brackets for every branch condition.

for (int i=1;i<=m;i++) {
    if ((A[i]>minim) && (A[i]<maxim)) { 
        nn1++;
    }
}
for (int j=1;j<=n;j++) {
    if ((B[j]>minim) && (B[j]<maxim)) {
        nn2++;
    }
}

Answer 3

Take care of paranthesis when dealing with ifs :

if ( (B[j]>minim) && (B[j]<maxim) )

   |                              |
   V                              V

 Add these 

So, your code should be:

int nn1,nn2;
for (int i=1;i<=m;i++) if ( (A[i]>minim) && (A[i]<maxim) ) nn1++;
for (int j=1;j<=n;j++) if ( (B[j]>minim) && (B[j]<maxim) ) nn2++;
if (nn1>nn2) cout<<"1";
if (nn1<nn2) cout<<"2";
if (nn1=nn2) cout<<"0";

return 0;
}

Answer 4

Missing parentheses around the whole condition :

for (int i=1;i<=m;i++) if((A[i]>minim) && (A[i]<maxim)) nn1++;
//                       ^                            ^

Answer 5

You forgot the ( ) in if statement.Try this :

int nn1,nn2;
for (int i=1;i<=m;i++) if ((A[i]>minim) && (A[i]<maxim)) nn1++;   //note extra ()
for (int j=1;j<=n;j++) if ((B[j]>minim) && (B[j]<maxim)) nn2++;   //note extra ()
if (nn1>nn2) cout<<"1";
if (nn1<nn2) cout<<"2";
if (nn1=nn2) cout<<"0";
return 0;
}

Answer 6

In C++,there should be a complete "()" after the "if" and what in "()" is the condition. So,the code you showed is if(A[i]>minim) && (A[i]minim) && (A[i]