c - C中用0填充字符

Question

我试图将一定数量的零填充到字符数组的开头，该数组稍后将被读取为整数。这是我的代码:

// charArray is '123' right now
// want charArray to be 00123
// Shift elements in array forward 'difference' times
// difference is amount of 0s to be padded to beginning of string, difference = 2 here
for (i = strlen(charArray) - 1; i >= 0; i--) {
    charArray[i+difference] = charArray[i];
}

这就是我遇到问题的地方。下面代码运行的方式，charArray是??123

for (i = 0; i < difference; i++) {
    y[i] = 0 - '0';
}

如果我这样做:

for (i = 0; i < difference; i++) {
    y[i] = 0;
}

我的字符串提前终止。有什么想法吗？

Answer 1

要设置填充区域，只需使用以下代码:

for (i = 0; i < difference; i++) {
    charArray[i] = '0';
}

或者可能:

memset(charArray, '0', difference);