Substring Finder
C
Medium
3 views
Problem Description
Perform a substring search in a string. Implement strstr() without manually doing it. Count matching characters and return them.
Official Solution
#include <stdio.h>
int main() {
char str[200], sub[100];
int i, j;
int mainLen = 0, subLen = 0;
int matchCount = 0;
int found = 0;
printf("Enter main string: ");
fgets(str, sizeof(str), stdin);
printf("Enter substring to search: ");
fgets(sub, sizeof(sub), stdin);
// Remove newline characters if present
for (i = 0; str[i] != ' '; i++) {
if (str[i] == 'n') { str[i] = ' '; break; }
}
for (i = 0; sub[i] != ' '; i++) {
if (sub[i] == 'n') { sub[i] = ' '; break; }
}
// Calculate lengths
for (mainLen = 0; str[mainLen] != ' '; mainLen++);
for (subLen = 0; sub[subLen] != ' '; subLen++);
// Substring search
for (i = 0; i <= mainLen - subLen; i++) {
matchCount = 0;
for (j = 0; j < subLen; j++) {
if (str[i + j] == sub[j]) {
matchCount++;
} else {
break;
}
}
if (matchCount == subLen) {
printf("Substring found at index %d, length matched = %dn", i, matchCount);
found = 1;
// If you want all occurrences, do not break here
break;
}
}
if (!found)
printf("Substring not found.n");
return 0;
}
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