printf输出垃圾而不是特定字符 [英] printf outputting garbage instead of specific characters

问题描述

好吧，我对printf()感到奇怪.它在屏幕上输出垃圾.我猜这与记忆有关.看看:

Well I've weird problem with printf(). It's outputting garbage on screen. It's kind of connected with memory I guess. Have a look:

char string1[] = "SAMPLE STRING";
char string2[20]; // some garbage in it

/* let's clear this madness*/
int i = 0;
for (i; i < 20; i++) string2[i] = ' ';   // Space, why not.

printf("output: %s", string2);

输出

output:      ╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠SAMPLE STRING
// ten spaces and random characters, why?

推荐答案

因为C字符串需要NUL终止.这意味着您字符串的最后一个字符必须为'\0'.这是printf(和所有其他C字符串函数)如何在字符串完成时知道的.

Because C strings need to be NUL terminated. This means the last char of your string must be '\0'. This is how printf (and all other C string functions) know when a string is finished.

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