Question

you may not use any of the C-string library functions such as strlen(), strcpy(), strstr(), etc. You must write your own. You might consider writing helper functions to do tasks that many of these functions require, e.g. finding the last character of the string, and then use those helper functions where convenient.

This function finds all instances of the char ‘target’ in the string and replaces them with ‘replacementChar’. It also returns the number of replacements that it makes. If the target char does not appear in the string it returns 0 and does not change the string. For example, if s is “go giants”, target is ‘g’, and replacement is ‘G’, the function should change s to “Go Giants” and return 2.

int replace(char *s, char target, char replacementChar)

Answer 1

#include <stdio.h>

int str_length(char* s)
{
int count = 0;
while (*s) {
s++;
count++;
}
return count;
}

int replace(char* s, char target, char replacementChar)
{
int len = str_length(s);
int i, count = 0;
for (i = 0; i < len; ++i) {
if (s[i] == target) {
++count;
s[i] = replacementChar;
}
}
return count;
}

int main()
{
char str[100], target, replacement;
int count;
printf("Enter a string: ");
scanf("%s", str);
printf("Enter target character: ");
scanf(" %c", &target);
printf("Enter replacement character: ");
scanf(" %c", &replacement);
count = replace(str, target, replacement);
printf("modified string is %s and number of occurances of %c were %d\n", str, target, count);
return 0;
}

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