C_输入一个整数N，输出从0~N（算法思考）

1.for循环实现

#include <stdio.h>
#include <time.h>

clock_t start, stop;
double duration;

void printfN();

int main(){
    int N;
    printf("Pleade enter a number: ");
    scanf("%d", &N);
    start = clock();
    printfN(N);
    stop = clock();
    duration = ((double)(stop - start))/CLK_TCK;
    printf("duration = %f
",duration);
    return 0;
}

void printfN(int N){
    int i;
    for(i=0; i<=N; i++){
        printf("%d
",i);
    }
}

2.递归实现（有问题，思考——算法的执行效率与输入规模的关系）

#include <stdio.h>
#include <time.h>

void printfN();

clock_t start, stop;
double duration;

int main(){
    int N;
    printf("Please enter a number:");
    scanf("%d", &N);
    start = clock();
    printfN(N);/*12000程序无法运行*/
    stop = clock();
    duration = ((double)(stop - start))/CLK_TCK;
    printf("duration = %f
",duration);
    return 0;
}

void printfN(N){
    if(N){
        printfN(N-1);
    }
    printf("%d
",N);
}