/in/foo.c:3:0: warning: ignoring #pragma warning  [-Wunknown-pragmas]
 #pragma warning(disable:4996)
 
/in/foo.c: In function 'main':
/in/foo.c:10:3: warning: implicit declaration of function 'itoa' [-Wimplicit-function-declaration]
   itoa(sum,s1,10);
   ^~~~
/in/foo.c:11:7: warning: implicit declaration of function 'strlen' [-Wimplicit-function-declaration]
   k = strlen(s1);
       ^~~~~~
/in/foo.c:11:7: warning: incompatible implicit declaration of built-in function 'strlen'
/in/foo.c:11:7: note: include '<string.h>' or provide a declaration of 'strlen'
/in/foo.c:19:5: warning: statement with no effect [-Wunused-value]
     for (t; s1[t+1]!='\0'; t++)
     ^~~
/in/foo.c:5:12: warning: variable 'k' set but not used [-Wunused-but-set-variable]
  int i,j,n,k,sum=1;
            ^
/tmp/ccNLa3zs.o: In function `main':
foo.c:(.text.startup+0x47): undefined reference to `itoa'
collect2: error: ld returned 1 exit status