Write a function substr() that will scan a string for the occurrence o

1.	Write a function substr() that will scan a string for the occurrence of a give substring. the prototype of the function would be:char substr(char string1,char string2);The function should return a pointer to the element in string1 where strig2 begins. If string2 doesn't occur in string1 then substr() should return a NULL.For example, if string1 is "Ena Meena Deeka", and string2 is "Meena" the substr() should return address of 'M' in string1. Write main() function also that uses the function substr().
Answer» #include <iostream.h> #include<stdio.h> char get_substr(char sub, char str); int main() { char substr,str; cout<<"Enter the string :"; gets(str); cout<<"\nEnter the substring :"; gets(substr); substr = get_substr(substr,str); if (substr!='\0') cout << "substring found: " <<substr; else cout<< "substring not found"; return 0; } char get_substr(char sub, char str) // Return pointer to substring or null if not found. { int t; char p, p2, start; for(t=0; str[t]!='\0'; t++) { p = &str[t]; start = p; p2 = sub; while(p2!='\0' && p2==p) // check for substring { p++; p2++; } /* If at end of p2 (i.e., substring), then a match has been found. / if(!p2) return start; // return pointer to beginning of substring } return 0; }

Write a function substr() that will scan a string for the occurrence of a give substring. the prototype of the function would be:char substr(char string1,char string2);The function should return a pointer to the element in string1 where strig2 begins. If string2 doesn't occur in string1 then substr() should return a NULL.For example, if string1 is "Ena Meena Deeka", and string2 is "Meena" the substr() should return address of 'M' in string1. Write main() function also that uses the function substr().

Answer»

#include <iostream.h>

#include<stdio.h>

char *get_substr(char *sub, char *str);

int main()

{

char *substr,*str;

cout<<"Enter the string :";

gets(str);

cout<<"\nEnter the substring :";

gets(substr);

substr = get_substr(substr,str);

if (substr!='\0')

cout << "substring found: " <<substr;

else

cout<< "substring not found";

return 0;

}

char *get_substr(char *sub, char *str) // Return pointer to substring or

null if not found.

{

int t;

char *p, *p2, *start;

for(t=0; str[t]!='\0'; t++)

{

p = &str[t];

start = p;

p2 = sub;

while(*p2!='\0' && *p2==*p) // check for substring

{

p++;

p2++;

}

/* If at end of p2 (i.e., substring), then a match has been found. */ if(!*p2)

return start; // return pointer to beginning of substring

}

return 0;

}