tot = 0;
for(i = 0; i < strlen(s); i++)
    if(s[i] == 1)
        tot++;
printf("There are %d character(s) '1' in the string.\n", tot);

用計時函式測試這段程式的執行時間隨著字串長度的變化規律。如何改進？

#include<stdio.h>
#include<time.h>
#include<string.h>
#define MAXN 100000 + 100
char s[MAXN];
int main()
{
    int
 
 i, tot = 0;
    FILE *fin;
    fin = fopen("data.in", "rb");
    fgets(s,sizeof(s), fin);   

    for(i = 0; s[i] != '\0'; i++)
        if(s[i] == '1') 
            tot++;
    printf("%d\n", tot);
    printf("Time used = %.2lf\n", (double)clock() / CLOCKS_PER_SEC);
    fclose(fin);
    return 0;
}