为什么我的程序无法在C中打印真实结果

Question

I've found a code about finding longest string in an array and print it with strrev(); function. My code works successfully, but if my first string was larger than other strings my program does not understand.

This is my prototype:

void LongStr(char str[][50],int n);

and This is my Main() function:

int main()
{

    char str[size][wsize];
    int n;

    printf("\n How many words to accept:- ");
    scanf("%d",&n);

    printf("\n Enter %d words:- \n \n",n);

    for(int i = 0; i < n; i++)
    scanf("%s", str[i]);

    LongStr(str,n);

    return 0;
}

and this is my LongStr(); function:

void LongStr(char str[][50],int n)

{

    int Max = strlen(str[0]);
    int len;
    int c;

    for(int i = 1; i < n; i++)
    {
    len = strlen(str[i]);

        if( len > Max )
        {
        c = i;
        Max = len;
        }

    }
    printf("\n The longest string with reverse model is: \"%s\" \n \n",strrev(str[c]));
}

Example:

FirstString

SecondLongestString

ThirdString

output: strrev("SecondLongestString");

Example:

FirstString

SecondString

ThirdLongestString

output: strrev("SecondLongestString");

Example:

FirstLongestString

SecondString

ThirdString

output: crash!

Thanks.

Answer 1

If the longest string is the first c is never initialized, which makes it garbage and most likely a huge number to index the array.

You should initialize it to 0:

void LongStr(char str[][50],int n)
{

  int Max = strlen(str[0]);
  int len;
  int c = 0;
  // ...
}

PS: although this problem doesn't occur with len , I'd say it's probably good practise to initialize it to something too. In other words, initializing all variables is a good thing. However, I haven't code in C in a long time and I'm not sure if this is the norm.

Answer 2

Really simple it's just a missing piece in your code

int Max = strlen(str[0]);
int len;
int c;

You need to give the c a value that why it's not working because it doesn't have a base value so try to change your code to

int Max = strlen(str[0]);
int len;
int c = 0; // base value of 0