STL Problem

[medleyj]

Can anyone tell me why example A works and example B throws an exception?

vTempContents is a vector<string>. m_strItr is an iterator. m_strMarker is a string. m_fGlossOut is an ofstream object.

Example A

m_strItr = vTempContents.begin();
while (m_strItr != vTempContents.end()) {
if(m_strItr != m_strMarker) {
m_fGlossOut.write(m_strItr->c_str(), m_strItr->size());
}
m_strItr++;
}

Example B

m_strItr = vTempContents.begin();
while (m_strItr != m_strMarker) {
if (m_strItr != vTempContents.end()) {
m_fGlossOut.write(m_strItr->c_str(), m_strItr->size());
}
m_strItr++;
}

Thanks in advance.