QString.toInt() doesnt work - Error: invalid operands to binary expression ('const char *' and 'const char [14]')

Question

我有这个代码：

QString carda = "000123";
QString queryStringAnet("SELECT * FROM [records] WHERE ([user]='" + carda.toInt() + "' AND [apl]='"+apl+"' AND [tasktype]='"+taskType+"' AND [taskkind]='"+taskKind+"' AND [timestamp]='"+timestamp+"')");

以及当我使用 carda.toInt() 时从 QString 到 Int 的转换我有这个错误：

error: invalid operands to binary expression ('const char *' and 'const char [14]')

和警告：

warning: adding 'int' to a string does not append to the string
use array indexing to silence this warning

我不明白为什么 QString.toInt() 不会工作...有什么想法吗？

Answer 1

I dont understand why QString.toInt() wont be working... any idea?

问题是在 qt 中你不能将字符串和数字连接在一起...

实际上你甚至不需要将字符串 carda 转换为整数，因为那是一个 QString

而只是做：

QString queryStringAnet("SELECT * FROM [records] WHERE ([user]='" + carda + "' AND [apl]='"+apl+"' AND [tasktype]='"+taskType+"' AND [taskkind]='"+taskKind+"' AND [timestamp]='"+timestamp+"')");

QString.toInt() doesnt work - Error: invalid operands to binary expression ('const char *' and 'const char [14]')

QString.toInt() doesnt work - Error: invalid operands to binary expression ('const char *' and 'const char [14]')

qt

type-conversion

qt5

qstring