How can I find a missing number on integer array of 1 to 100 elements?

Answer 1

in c++ :
for(int a:arr)
if (a==number) cout<<a;

or:

for(int x=0;x<100;x++)
if (arr[x]==number) cout<<x;
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in second one it show aray's index

Answer 2

if you know the array should contain numbers from 1 to 100, then you can sort it and iterate through the values. when you find a value which isn't equal to its' index + 1, the missing one is on that position