如何通过在C字符串循环？ [英] How to iterate over a string in C?

问题描述

现在，我想这样的：

#include <stdio.h>

int main(int argc, char *argv[]) {

    if (argc != 3) {

        printf("Usage: %s %s sourcecode input", argv[0], argv[1]);
    }
    else {
        char source[] = "This is an example.";
        int i;

        for (i = 0; i < sizeof(source); i++) {

            printf("%c", source[i]);
        }
    }

    getchar();

    return 0;
}

这也并不工作：​​

char *source = "This is an example.";
int i;

for (i = 0; i < strlen(source); i++){

    printf("%c", source[i]);
}

我得到的错误

在将Test.exe 0x5bf714cf（msvcr100d.dll）未处理的异常：0000005：访问冲突在位置0x00000054读书时，

Unhandled exception at 0x5bf714cf (msvcr100d.dll) in Test.exe: 0xC0000005: Access violation while reading at position 0x00000054.

（德国松散翻译）

那么，什么是错我的code？

So what's wrong with my code?

推荐答案

您想要的：

for (i = 0; i < strlen(source); i++){

sizeof的为您提供了指针的大小，而不是字符串。然而，如果你已经宣布的指针数组它会工作：

sizeof gives you the size of the pointer, not the string. However, it would have worked if you had declared the pointer as an array:

char source[] = "This is an example.";

但如果你通过阵列的功能，这也将衰减到一个指针。对于字符串，最好经常使用strlen。并注意别人怎么说，有关改变的printf使用％C。而且，以mmyers评论效率考虑在内，这将是更好的移动呼叫strlen的圈外：

but if you pass the array to function, that too will decay to a pointer. For strings it's best to always use strlen. And note what others have said about changing printf to use %c. And also, taking mmyers comments on efficiency into account, it would be better to move the call to strlen out of the loop:

int len = strlen( source );
for (i = 0; i < len; i++){

或重写循环：

for (i = 0; source[i] != 0; i++){

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