Thread: Understanding Strings - Statements

Hey all,

I am having an issue here but i really don't understand what's happening. the code below asks the user to input a string and what letter does the user want to change and with what.

The problem is that from what i see it skips entirely my for loop and statement and doesn't print anything.

Please explain what's exactly happening and how can I fix that.

Code:

#include <stdio.h>
#define MAX 100


int main()
{
    char str[MAX];
    char let;
    char let2;
    int i;
    
    printf("Enter String: ");
    scanf("%s", str);
    
    printf("Enter character you want to change: ");
    scanf("%s", &let);
    printf("Enter character you want to replace: ");
    scanf("%s", &let2);
    
    for (i=0; str[i]!='\0'; i++)
    {
        if (str[i] == let)
            str[i] = let2;
    }
    printf("The new string is\n%s\n", str);
    return 0;
}

The variable let is a char, not a string. You cannot use %s to read a char. Try " %c" instead (notice white space).

Do you realize that a char can only hold a single character and that the "%s" format specifier only works with C-strings, not characters.

Also you should never use a function that doesn't limit the number of characters it will retrieve into a C-string? With the scanf() function you can use the width modifier to limit the number of characters the function will retrieve. Just be careful to leave enough room for the end of string character:

Code:

    char str[MAX];
...
    printf("Enter String: ");
    scanf("%99s", str);

Jim