View Compilation Error

0_0_31080379_8728.cpp: In function 'int main()':
0_0_31080379_8728.cpp:9:12: error: 'strlen' was not declared in this scope
  n=strlen(a);
            ^
0_0_31080379_8728.cpp:14:13: error: invalid conversion from 'char*' to 'int' [-fpermissive]
     temp=a[j];
             ^
0_0_31080379_8728.cpp:15:9: error: invalid array assignment
     a[j]=a[j+1];
         ^
0_0_31080379_8728.cpp:16:11: error: incompatible types in assignment of 'int' to 'char [100]'
     a[j+1]=temp;
           ^