Write an ARM function that will insert a second string into a first string at a

Question

Write an ARM function that will insert a second string into a first string at a specific offset and return a pointer to the new string. The C language driver code is:

#include <stdio.h>

#include <stdlib.h>

extern char * ins( char * string1, char * string2, int place ) ;

int main( int argc, char * argv[] )

{

            char s1[] = "String to insert into" ;

            char s2[] = " this is the string to insert" ;

            int place = 9 ;

            char * result ;

            result = ins( s1, s2, place ) ;

            printf( "s1: %s ", s1 ) ;

            printf( "s2: %s ", s2 ) ;

            printf( "resulting string: %s ", result ) ;

            exit( 0 ) ;

}

Use the library routine malloc to obtain space for the new string. mallocs input is a number of bytes in a1 and it returns a pointer to the obtained space in a1.

            a1 is the calculated number of bytes

            bl malloc          library routine

            a1 is a pointer to the obtained space

Explanation / Answer

char* ins(char* s1, char* s2,int pos){

int i,j,count=0;

char* res;

char *resop=(char*)malloc((strlen(s2)+pos+1)*sizeof(char));

int num=strlen(s2)+pos+1;

for(j=0;j<pos;j++)

{

*(resop+j)=*(s1+j);

count++;

}

for(i=0;i<strlen(s2);i++)

{

*(resop+count)=*(s2+i);

count++;

}

res=resop;

return res;

}

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