int lastIndex[NO_OF_CHARS]={-1} 如何;不同于 vector<int> lastIndex(NO_OF_CHARS， -1);？

内容如何

int lastIndex[NO_OF_CHARS]={-1};  

与内容不同

vector<int> lastIndex(NO_OF_CHARS, -1); 

？

我如何使用它(从@digital_hog答案的评论中复制(：

#define NO_OF_CHARS 256 
int longestUniqueSubsttr(string str) { 
int n = str.size(); 
int res = 0; 
vector<int> lastIndex(NO_OF_CHARS,-1); // i want to replace this with array 

int i = 0; 
for (int j = 0; j < n; j++) { 
i = max(i, lastIndex[str[j]] + 1); 
res = max(res, j - i + 1); lastIndex[str[j]] = j; 
} 
return res; 
} 
int main() { 
int t;
cin>>t;
while(t--) {
string s="";
cin>>s;
cout<<longestUniqueSubsttr(s)<<endl;
} 
return 0;
}