C语言编程，1+2+3+4+……N的程序，怎么也编不会

#include

<stdio.h>

int

main

(void)

{

int

a,i

int

n,sum

printf("1+2+3+…+n=???,请输入n,程序将给出计算.\n")

scanf("%d",&n)

printf("这个N取值过小,请重新输入.\n")

getch()

while(i

<=

n)

{

sum

=

0

sum

+=

i++

}

printf("1+2+3+…+n=%d\n",sum)

if

(n<3)

return

0

}

#include <stdio.h>

int main()

{

int n, nn

printf("input a number: ")

scanf("%d", &n)

for (int i = 1i <= n++i)

{

nn = 1

for (int j = 1j <= i++j)

{

nn = nn * j

}

printf("%d! = %d\n", --j, nn)

}

return 0

}

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